OpenDNS
I am sure most of you are aware of this site and the service, but I just wanted to post this in case there was someone who was not aware of it.
Many people pay alot of money for filtering software when they don't need to.
I use this for my home, between me, my wife and four of our daughters, we have 7 pc's running, not to mention, the Wii and wireless devices. By using this service it filters all devices without any installation software, which is good, because in my home, we use, Windows, Mac and Linux.
John
I know a few people who have used proxy services like www.Familink.com, in order to filter access, but it's always hard for someone to set up the router properly for this filtering, as wise kids can often get through the network settings on one or more of the computers at the house.
Having a router-based access control system is always the best way to secure homes/schools!
I remember evaluating OpenDNS awhile back when we were searching for a filter at our house. However, since we have a laptop, I wanted to secure it on the computer level, since the laptop may get used at other access points. If you need something like this, I recommend the K-9 Web Protection software. It works very well on both Mac and PC, it's free for personal use, and they have excellent customer support.
K9 Web Protection is the BEST!

Ah yes; I'm using it at my place as well; a very convenient (and free!) service. One downside is that when your net connection is down, and you try going to a site when the connection just starts to reconnect, you lose the address of the site you were going to since it switches to an OpenDNS search page instead of a simple "page not found" page.
They have to make money somehow, so I understand, but still...
One really nice thing about OpenDNS is they maintain their DNS records much more studiously than most ISPs, so if you need to see your new website in less than the standard 24-48 hours it takes to propogate a new DNS entry (for, say, www.opensourcecatholic.com), then setting your nameservers to OpenDNS's nameservers might help.
Advancing the faith.