You can use Debian's ARMEL packages (at least for N8x0) however this highly discouraged (especially here and I can expect to be flamed for simply mentioning it).

IMO the main issue with their packages is that packages are named differently by different maintainers and thus you will have dependency conflicts (you can have a required package but under a different name and dpgk & apt-get simply isn't smart enough to deal with it).

The "powers that rule" have declared that devs should use the official repos or don't bother. (Of course no one seems to have a problem when Opera does it). Let me enlighten you, young N900 user to the world that was the 770+N8X0: http://www.gronmayer.com/it/

EDIT: silvermountain beat me to it.

A little Googling never hurt anyone: http://natisbad.org/N900/index.html => http://natisbad.org/debian-n900/
Slim pickings but perhaps more are to be found...