I've just learned of a couple of good writing challenges in case my writing friends are interested.
Harlequin's Book in Three Months Challenge
The idea behind this is can you write a book as quickly as one of their professional writers which is write it in two months and edit it in one? They will be posting informational and inspirational articles every Monday. The challenge started on June 1st so they are already one week in, but I bet you can catch up!
Candace Havens Writing Game Challenge
Starting June 7th you can join her yahoo group to participate in the Writing Game Challenge. Each day she will draw two numbers, a word count number and a page count number. If you're writing a first draft, you would write the number of words for that day. If you're working on revisions, you will revise that number of pages. If you haven't participate in her Fast Draft or Revision Hell workshops, Candace has some great advice and can help you with those elusive disciplined work habits that so many writers struggle with.