I orginally read about this concept at Read. Write. Poem.
What you do is find a line from one of your poems and donate it to other poets to use by leaving it in the comments section. All other poets are allowed to take that line and use it as the first one in their own poem.
Send your completed new poem to poetswhoblog at yahoo. com to be posted on this site, along with your screen name and the link to your poetry blog.