I have a running list of maps that I've been made aware of:
Desert Duel
Namek
Dying Namek
Ice Wasteland
ROSAT
Cell games
Kami's Palace
South City (?)
Island (test map)
Now I believe that the maps above are either completed or close to it. Grega had mentioned that Namek had not been changed in a long time.
Buu's stomach (unfinished)
Dr. Gero's Laboratory (assuming unfinished)
Check-In Station (seen a pic of King Yemma so perhaps this is an actual map)
Other World Tournament (seen a pic of it on the facebook page)
Kame House (I think I've seen this picture on this website)
Battle Arena (I made this name up; seen this pic on this website)
Once again this is just what I think is going on =^_^=