I know somebody was looking for this a couple weeks ago.

Computer Memory Saver
Prevents memory loss on digital radios, clocks, door locks, and computers when disconnecting vehicle battery. Plugs into cigarette lighter socket. Uses a 9V battery to keep "memories" alive for up to four continuous hours.
http://buy.snapon.com/catalog/search.asp?partno=YA960

This one may be the same:
KAS-295A KASTER COMPUTER MEMORY SAVER
available here:
http://small-business-help.com/bte.html

 

Hey that was me looking for that. Now I am done with my sub install so I dont know if I will be disconnecting the battery anymore....but if I have to I will def. order that. Great find thanks!!