I was reading about this in the LINUX Networking Cookbook by Carla Schroder.
You can purchase routerboards or single-board computers (SBCs) to make your own routers, firewalls and wireless access points just like many of you purchase a motherboard to make your own computers. You can use a compact flash card or micro drive for storage.
Coupled with Linux you can have a sophisticated router at home that has a small footprint and low power consumption.
http://www.linuxdevices.com/articles/AT2614444132.html
http://www.routerboard.com/products.html
http://soekris.com/products.htm
http://www.pcengines.ch/
This may be the next "computer"I build at home!
- Rich