PF traffic shaping

Being doing some research to enable traffic shaping, even tho, I have only one box, powered on 24x7 behind the OpenBSD firewall/ router, I want to learn more about it.
Here are a couple of links I have gathered while Googling on the matter:

- Prioritizing empty TCP ACKs with pf and ALTQ
- A brief introduction to altq
- Why do clients running BitTorrent make my router's latency go through the roof?