Susan asked about writing sprints.
Though I don't do them myself, I think I can explain them.
Writing sprints are similar to setting the timer and writing for 30 minutes: no potty breaks, no coffee breaks, don't answer the phone, fold laundry or do anything except write. The beauty of writing sprints is that you are sharing them with a small group of writer friends, online or in person. After each sprint you compare word/page counts, take a breather and start it over again.
That's it in a nutshell. The goal is to write in any manner possible. And if I didn't explain it correctly, then I'm sure Cyndi will correct me. :-)
Write on!