After a recent ROM flash (a particular 6.5 ROM) left my USB inoperable, I discovered a VERY useful tip. Before you flash a custom ROM, place a copy of the shipped ROM for you device on the storage card. If you do this, if something goes wrong, you can copy that ROM to DIAMIMG.nbh on the root of the card and load it without USB (see link for details:
http://forum.ppcgeeks.com/showthread.php?t=40490 ).
If you DO NOT have this image on your storage card before your USB is broken, you will have to jump through hoops to get the ~ 100 MB file onto your phone, thanks to not having removable storage (I had to place it on a web server I controlled and download, which wasn't too bad with unlimited data plan and a good connection, but lesson learned). You might also copy the relocking ROM to your device so you can return it to a supported condition in case you need to do a return
