Wim pointed out Apt-Pinning for Beginners which is a system where you can safely mix and match components from Debian stable/testing/unstable. Wish I'd had this when I set up ufies on debian unstable ages ago!
There's some more advanced pinning examples at: http://www.debian.org/doc/manuals/apt-howto/ch-apt-get.en.html
Seems like you can pin versions using wildcards too.
You can also check out the sites about- Tons of interesdting stuff!!!