There are lots of stuff that might be on the top of your "to do" list, but this will just take a couple seconds.
You all know about the Bow of Elements (Ice)
What if you could allow it being upgraded to an epic version? I know that it drops from Ghosts of Perdition, so logically, if it was available for upgrade, it should be in the Necro 4 system through a seal of the black abbot. But i was thinking, why not make that item "Epic'able" through usage of Canith challenge ingredients? The thought just came to me, since many of the items from the challenges seems to have some sort of elemental bound to them... and this bow has a water elemental version! (might just be a pretty weak elmental :P)
Bleh, im just dreaming... wouldnt hurt to have an epic Bow of Elements (Ice) as a +6 longbow with 2d8 20x3, icy burst, ice blast, crushing waves and keeping the precise shot in it (or make it the only bow carrying the feat improved precise hot while holding it?)
Ah well... just an idea, just a crazy suggestion