If you want to do traffic shaping at the IP level, then look at iptables and tc. Here is a helpful google:
http://www.google.com/search?hl=en&i...tables+shaping
If you are only concerned about Apache, but want to let other services burst without interference then take a look at mod_throttle:
http://www.snert.com/Software/mod_throttle/
I think the best bet is to use tc and manage the traffic at the IP level, just use a different IP for Apache.