Here are some links that I’ve found to be very informative:

Colorado State University
Leafcutter Bees: http://www.ext.colostate.edu/pubs/insect/05576.html

How to Raise and Manage Orchard Mason Bees for the Home Garden
Author: Stephen Bambara, Extension Entomologist
Pub: By NC Cooperative Extension
URL:         http://www.ces.ncsu.edu/depts/ent/notes/Other/note109/note109.html

Increase Pollination With Mason Bees
Author: Susan Ward
Pub: May 28, 2002
URL:         http://www.suite101.com/article.cfm/3319/92210

Pollinator’s Paradise:http://www.pollinatorparadise.com
Owner: Dr. Karen Strickler (Pollination Ecologist)

This site is definitely for bee lovers of all types. There’s a wealth of information available. I particularly like the “Identifying Bee” section. There’s lots of good references for digging up all kinds of information. Great ideas for projects.