12 Rules for Choosing Domain Names

SEOmoz has has a great list of rules to follow when coming up with domain names, check it out:

1. Brainstorm 5 Top Keywords
2. Make the Domain Unique
3. Only Choose Dot-Com Available Domains
4. Make it Easy to Type
5. Make it Easy to Remember
6. Keep the Name as Short as Possible
7. Create and Fulfill Expectations
8. Avoid Copyright Infringement
9. Set Yourself Apart with a Brand
10. Reject Hyphens and Numbers
11. Don’t Follow the Latest Trends
12. Use an Ajax Domain Selection Tool

Most of those rules are straight forward, but you can read a complete description of them here.