iproxy allows you to forward localhost ports to the device---allows SSH over USB on jailbroken devices, or allowing access the lockdown daemon (and then to all of the file access, sync, notification and backup services running on the device).
Example :
./iproxy 2222 22 &
ssh -p 2222 root@localhost
Paul Sladen <libiphone@paul.sladen.org>
Man page written to conform with Debian by Julien Lavergne.