CubeSpeaker for my MobiBLU 1500i !
Only $30 bucks and it's got a built-in Lithium-Ion battery that'll pump out tunes for 5-6 hours on a single charge!
Coolest part? It came with a tiny USB to MiniUSB charger that fits on my keychain! Conveniently it's the same interface for my HTC Wizard phone, so now I have an emergency phone charger on my keychain, with no extra cost! W00t!