I often use the "--limit=20k" parameter to wget when I'm at work and want to download something and not affect our SSH connections. Unfortunately, apt-get doesn't have a rate-limiting parameter, so when I have 100MB of updates to pull in it can bog things down.

I found trickle, and it is packaged for Ubuntu/Hoary :)

mlambie@stormshadow:~$ sudo trickle -s -d 20 apt-get dist-upgrade

The throttling isn't 100% stable - it jumps around from 10-30kb/sec, but that's fine for my use.