yes
go to
http://plf.zarb.org/~nanardon/
and follow the instructions
i added the austria graz contrib source this morning (15MB)
there's LOADS of stuff there
make sure you select 9.2, the default is 9.1
make sure you enter the details into a terminal as root
(you can copy and paste it if you use the Konsole terminal)
once completed, you can start up Install Software, and chage the display to show "by source repositry"