This week it's a Griffin PowerJolt Battery for iPhone [$34.95 - TiPb store link]. You plug it into your car, you charge your iPhone with it, and if you need to know more check out Jeremy's excellent review.
You need a US shipping address to enter, and while you're free to tweet (and re-tweet!) as often as you like, we'll only count 1 tweet per day. We'll choose one tweeter at random to get the PowerJolt.
The give-away starts now and ends Sunday, March 14, 2010 at 12pm PT.