That's only one of the issues that http.debian.net attempts to address. In a nutshell: it works as an http-only content distribution network. It uses the network and geographic location to select the best online and up-to-date mirrors.
APT's sources.list one liner:
deb http://http.debian.net/debian stable main
Use /debian-backports for backports, and /debian-archive for archive.debian.org.
Originally introduced to the Debian mirrors community back in January, the code on the server and client sides has improved since. All is needed is squeeze's APT (or aptitude), but wheezy's and sid's will perform better.
Advantages and more details are discussed at the Debian mirrors redirector's website.
(Thanks to the early testers, everyone who has provided feedback, my friends at PuffinHost, and all the mirrors-related people, obviously including those who sponsor them!)