Out of the books already announced I'm looking forward to the Character guide/World compendium the most!

As far as suggestions for new books I would say the magazine stuff that many have already mentioned would be my top most wanted.

Another suggestion would be to gather all the 2000x material into one book:
2000x Cartoon episode guide
2000x Comics
2000x Action figure/Stactions photo guide

Surely that would make a nice 500-600 page book!