One of the most popular routers out there is the linksys
WRT54GL.
It is a 802.11B/G compatible router. It's most attractive feature is the fact that it has been designed to run open source firmware.
So if you choose (and just about everyone does because its the reason for buying it), instead of the firmware it comes with, you can install 3rd party firmwares such as:
DD-WRT
Tomato
Open WRT
These other firmwares give your router a level of customization not found in the default firmware. OpenWRT is essentially linux made for your router, it has no default GUI or routing configuration. DD-WRT and Tomato run linux also but they have very nice web GUIs that allow you do to most anything.
Edit: Oh, I guess one of the great things about this router, and more specifically the third party firmware is that it supports Quality of Service (QoS).
It allows you to control the network priority of applications. The benefit of this is that you can give gaming apps a very high priority, and things like bittorrent very low priority. This way your little brothers (or your own) torrent downloading does not affect your gaming.