Bright House has had a series of DNS outages this year. Comcast just released its new DNS Re-direct service in trial cities. (It's a test to see if anyone complains). Most of the Top 12 ISP's have been using Bear Fruit DNS tools for over a year. Re-direct and you spelled it wrong are just 2 of the tools.
BTW, OpenDNS just raised a second round of funding.
Lifehacker has 5 content filtering tools for your clients - or you can use Squid and offer URL filtering yourself, especially to businesses.