GetFreeDomain.Name
The site lists over 40 free domain and free short subdomain providers with full DNS control (like A, CNAME, MX, NS records), so these are not just simple redirects.
If you're looking for a free domain like co.cc but not necessarily co.cc, you have to check this site out. It will give you a clue of what your options are.
You can also comment and post reviews on all listed providers.