As part of my home networking project, I have recently installed and configured Smoothwall. I used an old P100 that I had hanging around, threw in 3 NICs and set up smoothwall. So far so good, I really like the flexibility and power of this unit. The other part that I think is interesting is the ability to add content filtering to the box. This is not something that I need now, but I imagine that it would be really important for people who have kids.
Anyway, the new machine will be my new backbone router.