This is your chance to be a beekeeper without all the commitment of a honeybee colony.  Both mason and leafcutter bees are easy to care for.  These two species will not sting unless you physically handle them, and even then, if you are gentle, they won't sting. The maintenance is minimal, just set up the house for them, make sure it is near flowers and mud, and you are set! They do all the work, and the following Spring you have another round of cocoons to repeat the cycle!  If you have a vegetable garden, this is a great way to insure pollination!