It would be a good idea to integrate support for XEP-0144 Roster Item Exchange. With this external IM transports would have the possibility to submit nicknames/aliases for ICQ contacts for example and people won't have to rename all the contacts by hand. This would enable people to migrate without greater problems to XMPP:
I like the idea. Care to submit a patch?
Sadly I have no idea of programming in this category. I'm more someone who works with PHP and MySQL.