Twitter is a Trademark name, thus it is an infringment to use the word "Twitter" in your domain. My advise would be to let this domain expire and forget about it.
There are so many well established websites using the word tweet which is also a trade mark of Twitter.
I cannot say that twitterto.com violates infringement without further investigation. It will become a violation if the source or the owner of it has gotten no permission from Twitter. If this is infringement better to forget about it just like what have said by one of the commentators here.
No good.... You should not try to get a domain name that contain trademarks of well-known companies/websites
I think that people are just so scared to run with a domain that contains a trademark within it because people are so fast to jump forward to shout DROP IT! BIN IT! SELL IT! I think that you are ok to use the domain that you have registered as long as its aimed towards the improvement of the Twitter branding, so creating a high quality application for users to use FREE (has to be free otherwise you will get a lawsuit slapped on you) would be a good move. I am in talks with a creator at the moment to create me an application that will be placed on a Twitter domain name, after looking around the web to see if there was anything that outlined the purchase of such a domain for use of not making a profit is against the law. Not found anything yet. I know there is the TM in there, but your not earning on the site and so if they want you to remove it they will contact you.
If a website is free for users that doesn't mean that the owner doesn't earn anything (eg: DigitalPoint is free, but the owners earns from adsense). The point is to not earn money directly from a product or service using the "twitter" name.
It doesn't matter if you don't make a cent off the site. The bottom line is that you are inadvertently representing the company against their will by having their name in the domain name. With that being said, they have EVERY right to force you to take your site down at any given moment. Even if you are glorifying and praising them. All they have to do is send you a C&D based on reason of "commercial confusion" and it's over. But, some people would just rather learn the hard way.
Thank you all. I agree that it was my mistake registering this domain. By the way I also had NatGeo.info but I let it expired and I'll do the same with this domain as well.
Like BlackIceCreations said, I don't think you will have no problem with the twitter TM. I also have a domain including Twitter TM (TwitterColors.com) that I'm still not sure if I want to sell or keep because I'm not having the time available to implement the project soon. Saying that, I'm not sure if TwitterTo.com has any value besides the regfee unless you really have an idea for some twitter based application where the good keyword is To.