You Don't Want One of These
Below are some examples of what you do not want as your domain name.
Any domain with the word at in it. At is also used as @ in an email address. People do not know what to do with this. Example your domain ends up with some people emailing You@Home.com instead of You@AtHome.com
An absurd example of course. The rule is as short as possible to elimate as many errors in typing or memory as possible.
A domain that only makes sense to you and you only.
Unless people are counting their key strokes there isn't a lot of chance that you will have any visitors.
If you have a name that could have numbers or letters subed for words you had best stay clear of these or be willing to acquire about every variation.
Another example of needing a lot of luck to have people enter the right address correctly. (hint--jordon instead of jordan)