I don't think it is hugely important. I have stopped using the common dashed domain thing though, where you have you main keyword in there.
I try and get something that may help my site get the click. People generally surf for information, so if I was making a site on blue widgets, I might have something like bluewidgetcentral.com or something like that.
I basically go for:
- keyword or related keyword in domain - a word that tells the visitor that my site is the best site (central in above example).
This may not make much sense because I am tired, but hopefully you see what I am trying to say.
Some say it has nothing to do with it but I tend to disagree. I started out thinking that if the domain name had your keyword or product in it you would rank higher. People will argue that is because you have the site optimized for that keyword. That sounds logical.
An easy to remember domain name might help you get type in traffic if the visitor remembers your name at a later time and I too am all for having your domain name say what the site is all about.