This can be a sticky issue. There are many such sites, both positive and negative, and commercial and non-commerical. For example:
These are trademarks and fall under trademark laws. That is different from copyright.
Some trademark owners are more protective than others. In any case, they will have to sue for trademark infringement to have the domain taken away.
LEGO is a good example of a very protective owner.
LEGO says on their site regarding use their trademark:
The LEGO trademark should not be incorporated into an Internet address. Internet addresses have become useful tools for people to identify the source of a homepage. Using "LEGO" in the domain name would be creating the misleading impression that the LEGO Group sponsored the homepage.
They aggressively pursue domain names with "lego" in them.
However, as stated here in response to the LEGO issue, there is an exception for non-commercial sites.
Disclaimer from wellsfargosucks.com:
This is a non-commercial gripe and consumer information site and is not associated with or condoned by Wells Fargo & Company. If you wanted to go the the official Web site for Wells Fargo & Company you can find it at www.wellsfargo.com. WELLS FARGO, WELLS FARGO BANK, and WELLS FARGO ONLINE are registered trademarks of Wells Fargo & Company, and are used herein for non-commercial, fair-use identification purposes only. This Web site is in no way affiliated with Wells Fargo & Company.
Even in commercial use, many trademark owners don't pursue registered domains at all.
It is, after all, a form of joint publicity. I suggest you do a search to gauge how many domains might already use that trademark. You might also want to approach the trademark owner to see how they feel about this. If they are fine with it, you might attempt to get it in writing.
In site content
Even those trademark owners who don't pursue domain names may be more protective of how their mark is used in content. You will likely need to use the ® symbol and include a disclaimer stating that your site is not endorsed or affiliated by the holder of the trademark.
Going back to LEGO, these are their published wishes:
... the trademark should appear in the same typeface as the surrounding text and should not be isolated or set apart from the surrounding text. In other words, the trademarks should not be emphasized or highlighted. Finally, the LEGO trademark should always appear with a ® symbol each time it is used.
This is what Stack Exchange has done on the new LEGO site:
LEGO® is a trademark of the LEGO Group of companies which does not sponsor, authorize or endorse this site
I am not a lawyer, and you should consult one when dealing with trademark and copyright law if you are betting your business on it.