Word of mouth works well if your services are fantastic and you are setting up in a small community or rural area. It has the reverse affect if you fail to provide the goods or give sub standard service.
We operate the SA's #1 VoIP and Hosted PBX Provider Listing, Research, News and Information portal in SA, and have just released a new site and section to include WISP's. I have a number of areas which you can get involved. You are welcome to contact me via the website: www.whichvoip.co.za