I'm going to register a domain name. My site is going to be about the halo community (e.g. downloads, cheats, discussion, etc). Trying to think of a name...halocommunity.net? haloinfinity.com? halo123?
Sorry to ruin your day. Companies are getting much stricter on domain name trademark violations now days. Hate to see you do all that hard work and then get a cease and desist letter from some attorney.
Just go with something that includes Halo. I mean.. unless you sell something and make a lot of profit under name "Halo" I highly doubt there will be any trouble. Especially if you're just going to make a community, or regular fan-site.
I personally haven't heard of any case that someone has been sued for using something like "HaloWarsCentral" or "Gta-sanandreas" or whatever game name for fan site. In the end Halo would probably even sell some more copies because of that site..
I don't think any game company would be that stupid to shut down some community just because it uses some game name in its domain or whatever. Company would probably get a lot of bad rep. sell less in the future for that..