If I write something on fluther, does fluther own my words?

You own your own words.

I just ask, because facebook owns everything you put up, according to their ToS.

You own your own words in all the various ways that can imply, including responsibility.

See “Copyright Information” here, under “Terms and Conditions.”

…and Fluther Terms & Conditions states:

Any content posted on this site may be used by Fluther for any purpose.

You may redistribute, reproduce and/or display any posted content on this site, provided :
1. You prominently mention Fluther.
2. You attribute the original author (unless they are anonymous) as they are listed on Fluther

In short, you own your words, but you grant us a license to use them in perpetuity.

We’re thinking of redoing the ToS using Creative Commons, but the gist will be about the same. You own your content, but we have rights to use it.