i've recently came across interesting project for automatic mirror selection in debian's apt, namely httpredir. after about two weeks of using it i must say it works like a charm! :) mirrors are selected very reasonably, which results in fast download speeds and up to date repos. and all of this works out of the box – all one needs to do is to change URLs to repos from something like:
deb http://ftp.pl.debian.org/debian testing main
to:
deb http://httpredir.debian.org/debian testing main
…and that's it! everything else is done automatically, based on your source address.