Hmm...  I'm gonna have to agree that Dimahoo is truly a fun game, but my most frequent plays have been in Kawaks, and I've been playing Marvel vs Capcom, Xmen vs Street Fighter, Mars Matrix, and also I play a lot of Guwange using Raine.  Mame supports this game fine, but I like the way it looks more in Raine.  If you love creative vertical shooters definitely give Guwange a try.  My mame's been a bit dry recently because all people around here play is Marvel vs Capcom 2, so I've been getting super good at that game, got it for my roomies modded ps2.  I also recently umm.. acquired Guilty Gear XX Reload for ps2 as well, haven't really had a chance to get everyone around here into it, but I played it a bit before, and that game is seriously the best Guilty Gear there is.  It's hella fun to start up some huge combo and see what you can get to connect.
     -Games I used to play obsessively but have calmed down from:
         King of Fighters 2002  (NrX)
         Rage of the Dragons  (Kawaks)
         Dodonpachi                (Raine)
         Black Tiger                  (Mame)
         Samurai Showdown 4  (NrX)
-Luke