Okay here is the deal. There is a site name modmyi.com, and modmyi is trademarked. I bought the domain imodmyi.com about a month ago. Could I get in trouble because my domain has a trademark in it? Thanks guys.
If your site doesn't use anything they use, then no.
Like Perter said above, if you don't offer same services/same content which they have then of course not.
If modmyi is a registered trademark, then yes, you could.
Just don't offer anything they offer and you should be okay.
They can claim the domain if you are impersonating them or domain squatting, IIRC.
If you look at the Legal Resolution section of this Wikipedia page, you can see the ways that they might take your domain.
http://en.wikipedia.org/wiki/Cybersquatting
I don't think it's a good idea to copy domains, but it's your choice! :]