Short domain names are best. Also, if you have something like Long company-name, make sure you also register an abbreviated version of it, like LCNI.com (long company name inc). You can use it for additional things like email, makes stuff much easier to do like say an address over the phone.
Trust me, you don't want to be spelling somthing like "obscurecompanydomainname.com" a dozen times a day over the phone. This is something you can't easily change later.
Also, if you come up with "Super perfect company name" make sure you google it thoroughly to make sure you're not duplicating someone else too much. Sure, you can use something that's similar to some other company, but if there's dozens of companies with similar names, especially in the same field, you might want to reconsider.
Also, if you incorporate your company you pretty much have to just make sure you don't overlap a company name in the same state. So if you're in california, it's most important to make sure you check california for similar company names.
You can also do a "doing business as" if you decide on one company name but find something short is ok. So if you incorporate with the state as "My Awesome Company, LLC" you can file for a DBA as something shorter like "Awesome LLC" or "MAC.com".
That's probably more information than you really wanted, though.
answered Oct 22 '12 at 13:59