Build Your Own PBX
Kerbo writes "Kerry Garrison has written up a complete guide to building your own PBX with Asterisk@Home to create your own working PBX system. In the article, he shows how you can build a complete, working system for under $20 (assuming you have some old hardware laying around the house)."
It you just opened your own cottage industry style consulting business out of your home, something like this could make you look like a bigger business. I could see the advantage to that. The features of the system would be handy too for a new and very small business.
http://www.busyweather.com/