Nightlife, no place beats Roppongi. Kung dance club na European style ang trip mo, you won't go wrong with Gaspanics.
Especially for YANKEES (white dudes)

If you're a pinoy, Shinjuku, Shibuya, Kinscho, and Yokohama is heaven. Jobelle Salvador and Jean Garcia works in Kinscho, kabanggan siko kumbaga.

But nicolodeon made a great summary of what to do in Japan.