Edit: I'm seeing a lot of hits to this page from people searching for a 3.0.2 Restokin build. That's not on this post, but I took a stab at it in my First draft talent builds post.
Let's talk about Restokin. This is the hybrid Balance/Resto spec for druids. I've also seen it called DS/NS (for Dreamstate/Nature's Swiftness). The defining feature is a mostly even split of talent points between Balance and Restoration, usually taking Moonkin form in Balance and Nature's Swiftness in Resto.
I've spent a lot of time in variations on this spec and I enjoy it quite a bit. I don't remember the details, but the last third of my leveling experience with Alamein was as a Restokin. I specced into it sometime shortly past level 50, and kept it up for quite a bit after I hit 70. My first several Karazhan runs were as a Restokin. Since then, I've mostly switched between full Resto and full Balance, with a good chunk of time in Feral learning how to tank. I got tired of constantly respeccing, so last week I jumped back into Restokin.
Let's be clear: a Restokin is a compromise. In most situations you won't DPS as well as a full Balance build, and you usually won't heal as well as a full Resto build. My goal was to get to a single spec where I could heal Heroics, run battlegrounds, and run dailies with equal ease. The Restokin is great at this. I suspect it's good in Arena too, but I'm a total Arena noob so I won't presume to offer advice in that direction.
TalentsHere's my current 31/0/30 Restokin build. (Edit: Talent build link no longer works with the launch of 3.0.2.) First, I would NOT recommend this particular build; I tried a few things to be different and I'd do it differently if I tried again. I was going to show my preferred build, but it will be obsolete in a couple weeks anyway. The basic principles, however, will still be the same.
Some of the key talents:
BalanceInsect Swarm: It's easy to forget how useful this spell is. It doesn't go BOOM but it still puts out a good bit of damage, and the reduced chance to hit is helpful in both PvP and PvE.
Celestial Focus: I shouldn't have skipped this, the pushback resistance for Wrath is pretty important. I'm curious how this will play out when 3.0.2 hits because the pushback mechanism will change so much.
Lunar Guidance: Absolutely key. This talent means that I have more +heal as Restokin than I do in full Resto. It compensates for giving up tree form and the other Resto talents that add to specific healing spells. It also means that today a Restokin should stack Intellect. Not sure, but that may change some in WotLK.
Nature's Grace: Another great one to have. As a Restokin, you'll be using more Healing Touch and Regrowth than as a tree, so Nature's Grace will help you a lot.
Moonglow: This is an optional talent, depending on whether you want to focus more on pure DPS/HPS or on mana efficiency. It's actually more important for your healing side. If you want this, you'd sacrifice some points from Moonfury.
My current build skips most of the mana efficiency talents. I definitely feel the effects; in healing Heroics, mana has been a challenge but manageable. (Specifically: I haven't gone OOM yet, but I have been using a lot of Innervates and mana pots.)
Dreamstate: Another mana efficiency talent. This can be a huge benefit for Restokin — it's why they're often known as "DS/NS" druids. The synergy between Dreamstate and Intensity is huge. I suspect that with 3.0.2 I'll really want this back again, because mana management will be a lot more important.
Moonkin Form: This is why you're a Restokin. Great for soloing and battlegrounds. Moonkin Form + Barkskin is amazingly survivable, and is the closest thing to a short-term caster tank you'll see. Also not bad if you're healing an instance and adds come calling; it gives your tank some extra time to regain aggro.
RestorationNaturalist: You'll choose between this and Nature's Focus. Naturalist is better for instance healing and maybe AV; Nature's Focus is better for PvP.
Intensity: A no-brainer, especially since the lower-tier talents are otherwise optional.
Subtlety: Really useful for threat management when healing instances. I usually end up with 4 points in this. If I were focusing on PvP I might be inclined to shift points into Natural Shapeshifter, but I'd want to think about the dispel resistance of Subtlety, especially for Arena. Don't steal my HoTs!
Nature's Swiftness: Another spec-defining talent — moreso for Restokin than for pure Resto builds. Use this exclusively with Healing Touch. Here's a quick and dirty macro for it:
/stopcastingWowWiki has more complex NS macros that are worth checking out. Congrats: you now have a giant instant heal on a 3-minute cooldown. I just loooove dropping this in battlegrounds — there is nothing better for frustrating the opposition — but it's a great panic heal for instances too. And you're already healing in elf/tauren form anyway so you don't have to worry about tree form.
/cast Nature's Swiftness
/cast Healing Touch
Your remaining Resto points should be spent as you see fit. Gift of Nature benefits everything a little bit. Beyond that, you can focus on Rejuvenation with Improved Rejuvenation, Regrowth with Improved Regrowth, or Healing Touch with Empowered Touch.
PlaystyleYou'll heal in elf/tauren form and DPS in Moonkin form. You've got a lot of flexibility to adjust to different situations; make sure to use it.
Solo PvE: Nothing special here: you're basically a (slightly underpowered) Moonkin, and you'll solo the same way. I usually lead with Starfire and Moonfire, use Entangling Roots and Insect Swarm, then Starfire or Wrath as appropriate. Keep an eye on your Nature's Grace procs — it will make the cast time of Wrath less than the GCD, which can mess up your rotation if you're not careful. (I believe this is fixed in WotLK.) Don't forget your NS/HT macro panic button; it should get you around half your health back instantly.
Also: think about using melee on the last 10% of a mob's health to regen mana, as melee regens mana in Moonkin form. You'll kill the mob more slowly and take some damage, but you'll be at (for example) 80% health and 80% mana instead of 95% health and 40% mana. It'll speed up your solo work.
Group PvE: Don't be surprised to find yourself using Regrowth and Healing Touch a lot more than you do as a tree. You don't have Swiftmend and your HoTs don't tick as hard; you'll make up for that with direct heals. Nature's Grace will really help with this, especially with a few points in Improved Regrowth. Mana management will be your biggest issue; expect to use Innervate a lot, along with mana pots and maybe Drums of Restoration too. If you're having trouble, try moving talent points into Dreamstate and maybe Moonglow.
One of the advantages of healing in elf/tauren form is that you can attack a bit on the side, when you can spare the mana or GCD. Your first priority beyond healing should be to drop Insect Swarm whenever you can. The damage is nice, but the -2% hit will help your healing too. You can also switch to pure DPS at the end of a fight if you're OK on healing.
Battleground PvP: You do the most good in battlegrounds if you heal, so make that your first choice. Spread Lifebloom and Rejuv around liberally. Lifebloom is especially nice because it protects your allies from Purges. Use Regrowth for people in combat with more than 50% of their health.
Use your NS/HT macro for anyone who's down around 25%, or lower if they're in single combat. They'll love you for it! Watch for line of sight though. If you target someone who runs out of line of sight, your NS will go off but the HT will fail. Your NS buff is still active: you can either regain LOS and try HT again, or find someone else to give your insta-HT.
Use Moonkin form if you're sucked into melee combat or if the healing is covered by someone else. Cyclone is a great tool; look for someone casting a big spell or with a short-term buff like The Beast Within. Save your Cyclone for someone who's not currently targeted; you don't want to cause your allies to waste their attacks. Spread Insect Swarm around liberally; both the damage and the -hit are useful. If you're not getting pummeled, use Hibernate on animals that aren't being attacked. Hunter pets are an obvious target but cat or bear druids are better. Even if they trinket out of it, you've used up their trinket cooldown.
(There are probably interesting things about running a Restokin in Arenas, but I'll leave that to someone who knows Arena better than me.)
That's the nickel guide to running a Restokin. When talents get worked out a bit, I'll take a stab at what a WotLK Restokin would look like. Hm, would I rather have Swiftmend or Force of Nature? Decisions, decisions....