750Words is a journal website. It's not like LiveJournal or a blog or anything, everything you write is private instead of being shared with the world. The goal is basically to write three pages every day, of pretty much anything. You don't have to, but if you want to challenge yourself to it there's the option. Personally, I just use it to write early drafts of blog posts or to rant and get stuff off my chest without boring my friends. It's a pretty awesome little site.
And on May 1st, they're going to change it from free accounts to paid accounts, so they can afford to keep the site running. But anybody who had an account before May 1st automatically gets upgraded to a free lifetime account. I really recommend the site to anyone who either keeps a journal, wants to be a writer (I frequently use it to work out stories that I dream of writing but never actually get around to), or just thinks that someday they might possibly want this awesome free journal. Go get an account! It won't hurt, and if you ever decide to keep a journal you'll have access to a really nice online one if you sign up now, before they change it to paid accounts. Or you can just support the site and buy an account, that works too!