Fairly competent disc burning software - http://burn-osx.sourceforge.net/Pages/English/home.html
VLC, Handbrake, you know about.
The iStat apps are pretty nifty too - http://www.islayer.com/apps/
OnyX is useful to have (kind of a maintenance suite, I have it but I couldn't tell you when I last run it) - http://www.titanium.free.fr/pgs/english.html
For your IM needs, Adium is pretty comprehensive - http://adium.im/
A lot of people swear by CyberDuck for FTP - http://cyberduck.ch/
It's worth having a nose about on http://osx.iusethis.com/ as well. Lots of things, recommended by the folk who use them, which I think must be better than blindly downloading freeware. Of course, you might find a gem.
Don't neglect Preview.
It's actually got some pretty handy tools for colour correcting, cropping and so on. Worth exploring a bit with that and seeing if it'll meet your needs.
Oh, and I hope you enjoy the new shiny.
