From what I understand, co.cc rank lower than standard .tld's, which could make it hard for you to make a successful site.
I only use .co.cc domains for things like proxies and other sites that aren't of a massive importance.
To transfer ownership of a co.cc domain (which is what you'll do if you sell it):
CO.CC - Free Domain name registration + Free DNS service.
I highly recommend reading that page. ^