I'm anxious to try selling domains but have a question on where to find out if a name is trademarked or not. Is there any other legal stuff I have to watch out for?

Also, how close to a existing name is "unethical"? ie: domainsale.com and domainsales.com is this ok?

Thanks!

i think if you sell a domain that was intended to take away traffic from an existing domain (ie, yhaoo.com, or yahooo.com, or yaho.com, mircosoft.com, etc) then it is unethical...

From the U.S. Office of Patent and Trademark:

Trademark Registration of Internet Domain Names
http://www.uspto.gov/web/offices/tac/notices/guide299.htm

Also www.DomainState.com has a "tools" section that looks up trade marks in more countries. The "ethical" question is more legal becuase there are rules laws to cover that issue - they are abused a lot to.