750 Words is a site use often, nearly every day, to help clear my mind and jumpstart the writing process. It is a simple site that allows the writer to set up their own account. After writing it provides an analysis of the writing that is interesting.
There are other features that are interesting and fun as well. There are fun badges - badges for writing a certain number of days in row, badges for speed of typing, badges for number of words written. There is a monthly challenge, and ways to connect with others if desired.
The idea for 750 Words came from the idea of Morning Pages, which is writing three pages each morning on whatever ideas come to mind to write about. It's a kind of mind clearing process and a way to begin the creative process.
So if you are looking for a place to write just for the fun of writing you may want to check out 750 Words.