As a moonkin, first and foremost on my mind reaching the hit cap. Don't let anyone tell you otherwise, but hit is always worth more than damage. Because if you don't hit, how much damage are you doing?
And for the math conscious... 1 point of Hit rating is worth 1.09687 Spell Power courtesy of Graylo of Gray Matter. Sure, it's not a lot, but all else being equal, go for the hit. Hit would be especially important beyond the moonkin's own dps if the raid expects the moonkin to provide a debuff such as Improved Faerie Fire for the rest of the raid.
Most if not all raiding moonkin will talent for Balance of Power which brings the chance to miss down to 13% versus a raid boss. Assuming the raid's lucky enough to have a shadow priest (because goodness knows they were a rare breed on my server), the chance to miss will only be 10%. This means that the hit cap would be 341 or 263 hit rating depending on the presence of a shadow priest.
Now if we go to WoWHead and look at the leather caster gear with hit rating... wow, there is none prior to T7! Well, we're used to being the neglected spec. There's no reason we can't wear some cloth to make up for it.
So here's the list of spell hit gear to watch out for (or grind for). Some slots have more options listed than others since I try to go far enough down the list that there is something reasonably convenient to attain in the event heroics and thus badges are in short supply. I'm also assuming [Veiled Monarch Topaz] for all sockets unless following the socket bonus results in more hit or dps. As always, you can socket for spell hit as an option if your gear does not have it natively.
|[The Argent Skullcap]||61 hit||Icecrown quest - The Crusaders' Pinnacle|
|[Hat of Wintery Doom]||52 hit w/ socket||Tailoring BoE|
|[Necklace of Taldaram]||43 hit||Ahn'kahet (H) drop|
|[Emeline's Locket]||37 hit w/ socket||Icecrown quest - The Admiral Revealed|
|[Amulet of the Malefic Necromancer]||37 hit w/ socket||Icecrown quest - Poke and Prod|
|[Mantle of the Underhalls]||33 hit w/ socket||Icecrown quest - Mantle of the Underhalls (Alliance only)|
|[Spauldors of the Runeseeker]||28 hit||Un'goro Crater quest - The Activation Rune|
|[Hateful Gladiator's Cloak of Ascendancy]||34 hit||38,000 honor|
|[Dark Soldier Cape]||29 hit||Honored w/ Knights of the Ebon Blade|
|[Cape of Seething Steam]||29 hit||Halls of Lightning drop|
|[Water-Drenched Robe]||76 hit||Violet Hold (H) drop|
|[Ebonweave Robe]||68 hit||Tailoring BoE|
|[Robes of Lightning]||55 hit||Halls of Lightning quest - Whatever it Takes!|
|[Fleshwerk Shackles]||26 hit||Icecrown quest - Killing Two Scourge With One Skeleton|
|[Soothsayer's Wristwraps]||23 hit||Zul'Drak quest - Hell Hath a Fury|
|[Ebonweave Gloves]||51 hit||Tailoring BoE|
|[Lava Burn Gloves]||36 hit||Violet Hold drop|
|[Girdle of Bane]||48 hit||Utgarde Pinnacle (H) drop|
|[Plush Sash of Guzbah]||45 hit w/ socket||40 Emblem of Heroism|
|[Belt of Unified Souls]||42 hit||Culling of Stratholme (H) drop|
|[Sash of the Wizened Wyrm]||40 hit||Honored w/ Wyrmrest Accord|
|Forget it. There aren't any. Find some good DPS pants and socket hit if needed.|
|[Leiah's Footpads]||51 hit||Icecrown quest - The Air Stands Still|
|[Ring of Northern Tears]||39 hit w/ socket||Jewelcrafting BoE|
|[Brunnhildar Runed Ring]||39 hit||Storm Peaks quest - Making a Harness|
|[Shimmering Cold-Iron Band]||30 hit||Howling Fjord quest - Down to the Wire/Hasty Preparations|
|[Voodoo Signet]||24 hit||Gundrak quest - For Posterity|
|[Mark of the War Prisoner]||73 hit||Violet Hold (H) drop|
|[Figurine - Twilight Serpent]||58 hit w/ socket||Jewelcrafting BoP|
|[Rune of Infinite Power]||55 hit||Dragonblight quest - Mystery of the Infinite, Redux|
|[Grand Staff of Jordan]||68 hit||325 Stone Keeper's Shard|
|[Chilly Slobberknocker]||50 hit||Zul'Drak quest - The Champion of Anguish|
|[Stave of Youthful Sorrow]||44 hit||Icecrown quest - Tirion's Gambit|
|[Flameheart Spell Scalpel]||34 hit||Revered w/ Kirin Tor|
|[Ritualist's Bloodletter]||30 hit||Icecrown quest - Time to Hide|
|[Telestra's Journal]||39 hit||The Nexus (H) drop|
It can take several pieces, but it's definitely possible to reach 263, or even 341 hit rating before Naxx. It's even possible to do it with just quest and rep rewards if random drops just aren't happening or PvP isn't your thing. There's an unfortunate derth of decent hit gear in certain slots (shoulders, wrist, legs, and feet), but those can be focused on for sheer dps with other pieces.
Keep in mind that I just pulled out the gear with highest amount of hit rating I could find so in some cases there are greens listed that might be better passed over in favor of gear with less hit but more damage, but if you're having trouble reaching the hit cap, this is a good list to start with.
Final Note: The arena season is not up yet so I did not include any gear that requires an arena rating or arena points. There are a few pieces of very nice hit gear though if you can swing it.