I bought the Seidio 3200mAh battery after reading about it on the xda, hofo, and seidio sites. Yeah, my 6700 really IS a brick now, but battery life is incredible. I surf the web for 2-3 hours, have SPB Insight doing updates every 6 hours, and make about an hour's worth of calls every day. I now charge it up every five days or so. Previously, I'd be really lucky if I got 8-9 hours with the stock UStar battery!
BTW, don't buy it at the Seidio site. Go here (direct link -
http://www.htcdepot.com/seidio-3200m.../8A37A1570.htm) to the HTC Depot site instead.