http://www.homesew.com/
The search function above helps you find threads that get shifted down in the pile as new ones are added. It's a great timesaver. You also should go back to the home page and review how to navigate the site. There is an entire section called Links and Resources that is crammed full of great sites and reference spots.
That being said, The sites I like for free blocks are
www.quilterscache.com and
http://www.quiltbus.com/Free-Quilt-Blocks.htm
You may want to mute your speakers when you visit Quilters cache.