I would go to the library or Amazon and get Sharyn Craig's book "Setting Solutions", which happens to be my new favorite book. She has instructions for squaring blocks, setting blocks of different sizes (many samples from block exchanges), setting strange number of blocks etc. (like 5 or 7)
If you do a lot of block exchanges or sampler quilts where the block end up just a bit off, you need this book!
here's the amazon link. they have used copies for $12
http://www.amazon.com/Setting-Soluti...tt_at_ep_dpt_1