Unofficial Debian APT repository is available at http://people.debian.org/~sgolovan/debian/. It contains some packages which aren't in main Debian repository (or I don't like the way they built, or I use them for testing purposes) and I want them to be accessible not only by me:
Add the following lines to your /etc/apt/sources.list:
deb http://people.debian.org/~sgolovan/debian/ lenny main deb-src http://people.debian.org/~sgolovan/debian/ lenny main
and use apt-get to fetch and install packages.
All packages for lenny are built for i386 architecture.