If you have a Linksys router from their very reliable WRT54G family, you flash their Linux kernel with a hacked version.
DD-WRT is such a Linux version and I have heard a lot of good things about this patch. They say you can convert the $60 Linksys router into a $600 router. So it says all, this got a lot of useful features and you can convert your router to an advanced router.
This article explains how to flash the router.
Check with the official DD-WRT web site.
I first heard this from my boss and he was very excited about this. I might flash my router with DD-WRT too.