Im wondering if their is anything close to a fan made realm made in skyrim, not just an overhaul of skyrims systems and mods but a new world, quests, etc entirely fan made world, similar to nehrim.

I think it mean totalconversion mod or something similar?

Anything like that exist yet?

IIRC there is or was one in the works.. I don't remember the correct spelling but something along the lines of.. Mezoga?

It made Skyrim look like a little island from the map I've seen(it's been taken down, and it was displayed in the CK forums during the havok 64x64 ? bug testing).

Nothing like this yet, no.

None that have been completed yet.

If you liked SureAI's Nehrim, you should most definitely keep an eye on their sequel, http://www.moddb.com/mods/enderal. They seem to be making steady progress so far, and AFAIK they're also working on an English voiced translation, alongside the German version, this time around. Be sure to check out their YouTube channels as well, https://www.youtube.com/user/SureAITeam/videos and https://www.youtube.com/user/EnQueMedida/videos.

There's also http://www.andoran.com/, if you're interested, though I'm not currently aware of its status.