what are some ultimate items in this game?

[MaxiDuRaritry]

Imho the ultimate crafting exploit is to craft Shuriken^^

+1 Morphing sizing shuriken, of course. 1/50 the cost of a +1 weapon, and you can turn them into whatever weapon you want. Feel free to add additional enhancements for 1/50 the cost, as well. Then turn them into poison rings (from Dragon Compendium), enhance them as rings, and so on. Add the ringsword enhancement to all of your weapons, turn them into poison rings, then daisy-chain them together as long as you want. Best done with weapon enhancements that grant bonus feats, so you can DCFS them out for whatever you want.

Did I mention they're 1/50 the cost of a normal weapon? Because that makes those feats pretty cheap.

Even better if you've got access to a tooth of Leraje, from Tome of Magic. If you've got a spellthief in the party, he can buff all of your weapons with the 1/day CL 20 greater magic weapon, as well as the rest of your party. Feel free to hire one, if not.