Yes, you should follow @mariannewest (she always posts the freewriting prompts) and also @freewritehouse.
Marianne posts a new prompt (word/picture/phrase) every day and you're supposed to just sit down, set your stopwatch for 5 minutes and write whatever that prompt inspired you to write for the next five minutes. You can then post it, with the tag #freewrite ;) (I also recommend using other tags such as #writing, #fiction (if it is, of course), #isleofwrite, #blog, #story....But those aren't mandatory or anything. Well, usin the tag #freewrite isn't mandatory either, but it helps keep track of all the freewrites :)
Also, when you do post a freewrite, make sure to drop the link to it in the comments on @mariannewest's prompt post.
Helps other freewriters find you.
Hope I've made sense here and I look forward to reading what you have to say ;)