Seems like there's a ton of these for mages(Edwin with Robe of Vecna gets off 9th level pretty quick), but doesn't seem any such for clerics. Any items that speed up their casting time?

I wonder if a dual or multi mage/cleric can speed up cleric spell casting with the robes of vecna. Sure it shouldn't work that way, but it's certainly possible it would work. . .

The Amulet of Power comes to mind, IIRC.

I wonder if a dual or multi mage/cleric can speed up cleric spell casting with the robes of vecna. Sure it shouldn't work that way, but it's certainly possible it would work. . . Yes, this works. Aerie casting fast Cure spells is a big help (they're so freakin' slow)!

Well, Viconia is my cleric, so, any other items? Hell, even some "created" items that I could install that are insanely overpowered? I mean, I'm resisting the urge to use the Magi gear I installed from SP, cause it'll make Edwin more lethal than he is!

I'd say reducing casting time is a little over-rated, because until you have Alacrity/Improved Alacrity, it only helps on the very first spell. Once you cast a spell you can't cast another until the following round. Sure, a quicker casting time helps in some situations, but most of the protection based spells that need to be activated quickly have casting times of 1 or 2 anyway. Granted, healing spells take longer, but if you need to get a Heal off fast, chances are you did something wrong up to that point (why did you allow the character to get that injured before doing something about it?). For me, I usually wait until after combat to cast healing spells, and use healing potions during the battle. They always work (as in they can't be interrupted), they take effect instantly, and it doesn't take one of my characters out of action for a round while casting it.

But to answer your question, the only one that comes to mind is the amulet you get from Aran Linvail (referenced above). And that only decreases casting time by 1, so you aren't going to notice a big difference in a lot of spells.