Best deal on the “lean back” models is here:
http://shop.brando.com/google-nexus-s-usb-cradle_p05659c1265d106.html
http://shop.brando.com/google-nexus-s-2nd-battery-usb-cradle_p05660c1265d106.html
Interestingly, you can hack the dock by adding resistors, to get different results:
http://forum.xda-developers.com/showpost.php?p=12160799&postcount=40
http://forum.xda-developers.com/showthread.php?t=820275