I use this and it works great, even with my Diztronic case and OEM extended battery. I have it on my dash and it is quite sturdy.
http://www.ebay.com/itm/110786379810?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
http://www.ebay.com/itm/110786379810?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649