I should really mention the Linux firmware running on my router – which is dd-wrt. It gives many features not available in the stock Buffalo firmware which came installed on my router. I use the detailed port forwarding, support for DynDNS (who host my domain), loopback and numerous other features. Unfortunately it only supports routers with certain chipsets – have a look at www.dd-wrt.com (and be sure to read their wiki if you use torrents!).
Added wiki address since I’m getting lots of hits – http://www.dd-wrt.com/wiki/index.php/Torrent