I would add to this list of suggestions the ability to rate songs from Gizmo (ratings work great in the JRemote app, which uses a touchscreen 5-star graphic and syncs changes to the server on the fly.)
famu97, I also use Bluetooth audio, some of these problems were solved when my phone got a firmware upgrade from froyo to gingerbread 2.3.4. I now use hardware commands forward, back, and pause succesfully with Gizmo, whereas before the update none of these buttons worked. Gizmo has to be open on top as the primary app, however, because if it isn't Google Listen or Google Play will pop up occasionally and unexpectedly from hardware commands.
+1 to notifications and local file caching. I've got a 5gb monthly cap and still come close to the limit when I do a lot of network streaming (JRiver, netflix, podcasts, etc.)
Gizmo is awesome, I use it every day. Thanks for starting this thread, I look forward to the next stage of Gizmo development and hope that some of these ideas are implemented!