Yep, goodies for Streak! Mugen Power has made 1800mAh battery that replaces the original 1530mAh and a monster with 4800mAh to play.
Bigger one extends quit a bit but if you want 2.7 times the battery life you have to live with it.
4800mAh costs you $129 but 1800mAh is only $39
Dell Streak batteries at Mugen Power