For a few years, radioactive alchemist over on Gaia has been running SuWriMo, which is like National Novel Writing Month (NaNoWriMo) but spread over June, July, and August. The idea is to set a writing goal, divide it up by about 90 days, and get writing. I've done it for several years, and I've always had a lot of fun.
This year I asked her if I could take it to Twitter, and she agreed. So on June 1st I'll start posting my daily progress toward my #writegoal with the #suwrimo tag, and I invite all other writers to do the same.
You don't have to write a book over the course of the 3 months, but you can add to an existing book, or set goals for any sort of writing or editing project. And you can start early, keep going after August, or take time off if you have a vacation planned. It's a free-form writing exercise.
Many people track their progress through number of words written, but you don't have to. It can be number of chapters written, amount of short stories completed, whatever. The point of #suwrimo is to set a writing goal, talk with other writers, and have fun with it.
My goal will be to finish a draft of my current book by August 31st. I'm guessing that will take about 60,000 words, but I'll stop when the book's done. That's roughly 667 words a day--easily manageable, I think.
So, what's your goal? Post it on #suwrimo.