The web looks very different to me depending on whether I browse at home or outside my house. That's because my home DSL connection runs through a headless PC running IPCop and URL Filter before it goes to my wireless access point. IPCop is a Linux distribution that turns a PC into a network management appliance. URL Filter is an add-on that filters your choice of a variety of web content before it even reaches your computer.
I use IPCop as a DHCP server, caching HTTP proxy server, firewall, and console to monitor network traffic, and I have URL Filter configured to filter out ads. It's a great solution for the price (free), and open-source too!
Disclaimer: I posted this for informational purposes only, not to recommend that you block web ads. Most websites rely on advertising revenue for their continued existence.