Quilters Cache - LOTS!!! of blocks organized by size
Delaware Quilts - several traditional blocks organized by size
Gen X Quilters Quilt Block Library - picture library with links to several great block patterns and tutorials all around the web
Desperate Housewife's Quilt by quiltjane.com - 62 different block designs in all styles -- something for every hive of hive
Skill Builder Sampler by sewnbyleila.blogspot.com - 24 different block designs in all styles - this one has something for every hive too
Nine-Patch Quilt Block Patterns - many 12" blocks...all based on nine-patch type construction
Of course, the 3x6 photo stream is another great place to get inspiration!