I have seen quite a few great domains that i do not know if i can buy. How do i know which domains i will get sued for buying and which i will not?
If it is a great domain because it contains a famous name in it, then you can assume it is trademark infringement. The domain extension makes no difference. There is absolutely no way to determine what domain will get you sued - you can only limit your risk by staying away from a name someone else has established, especially if you intend to use it in a similar way. A good trademark search will run several hundred dollars per name, and still not be a guarantee. Common sense goes a long way. You could also read though all the posts on this board if you want to get a better idea of what is considered trademark infringement, but a lot of infringement is in a grey area and it will really depend on how aggressive the trademark holder is when in comes to protecting their domain. Don't register a domain to ride the success that has been established by someone else. They have earned the right to the name and its type of usage.