Using OpenDNS or Google DNS messes with content distribution networks. I don't recommend using them.
There's many reasons to run your own DNS:
* Improved performance, even if small.
* Avoid ISP incompetence (plenty ISP's don't honor refresh/expiry times or otherwise deliver a sub-optimal DNS service.)
* Ability to include alternative TLD's.
* To apply your own filtering (for everyone in the home).
* Use DNSSEC if your ISP doesn't.
* Run your own internal domain (e.g. for development purposes.)
* Hosting your own DNS and website from your home server.
etc. I'm sure others could come up with much more.