There is an Ioun Stone in ToB that grants +1 to WIS (and usable by anybody), but since that's the only thing it does, it's rather useless. The Sensate Amulet, sold by Diedre, also grants +1 WIS, but frankly I don't think it's worth the money. And lastly, Joluv sells the Axe of Hrothgar, which grants +1 WIS as well--a completely useless enchantment, since anybody who needs WIS (for anything other than Lore) can't use the Axe.....except for high-level Cleric/Thieves, and how many of those do you see running around?