Here's a write up I did a few weeks ago in the gear and storage forum that is applicable to Jeeps (rack is made for TJs and soon to be available for JKs)
http://expeditionportal.com/forum/showthread.php?t=13388
here's a pic of it:
http://expeditionportal.com/forum/showthread.php?t=13388
here's a pic of it: