What are some examples of Web filtering software products out there?

What are some examples of web filtering software products out there?
Three of the companies out there that make these types of products include:

1. SurfWatch - makes software that blocks sexually explicit material on the Internet.
2. SurfControl - Internet access control and filtering software for Internet and intranet protection. Provides service and support world wide.
3. Websense - provider of customizable employee Internet filtering solutions.

There are many others, just do a Goggle search. Most offer some type of free time limited downloaded for you to try out the software.