One of the pitfalls of the T-Mobile G1 is that it has pretty weak battery life. I don't think I'm the only one who is constantly trying to conserve battery or plugging in the G1 to a charger. Luckily, we have a Seidio Extended Battery for the G1 that packs 1400mAh (15% more) of charge without adding any unnecessary bulk.
We just received ours and will be following up with a full review after a couple days of testing. In the meantime, you can solve your own G1 battery woes by heading over to our Android Central store here!