ssh-multiadd adds multiple ssh keys to the ssh authentication agent.
These may use the same passphrase. When run without arguments, it
adds $HOME/.ssh/identity and $HOME/.ssh/id_dsa.  Alternative file
names can be given on the command line or in the configuration
file. It uses ssh-askpass if necessary. Unlike ssh-add, if any of
the keys use the same passphrase, you will only need to enter each
unique passphrase once, and keys that are already added will not
be prompted for again.

WWW: http://www.dakotacom.net/~donut/programs/index_s.html#ssh-multiadd