Ook wrote:
I have hundreds of bumblebees in my garden, and they are gentle like honey
bees and love my sunflowers and squash. Good polinators. I have noticed that
in the evenings, a lot of them find a nice cozy leaf or flower and curl up
and spend the night there. In the morning, I have a bunch of sleeping bumble
bees all over the garden. According to wiki they have colonies, but I'm
guessing they do not always spend the night there? Anyone else ever see
this?

Ook:

I know very little about Bees other than as you say, they are good
polinators. I live in California and last year I had these very laid
back, pugdy, very fuzzy, big black bumble bees show up during the
summer when my beans were in bloom. Literally, if I was trying to pick
my beans they would bump into my face (or arm or or) and then they
would simply carry on. It was lovely having them in my garden. I
garden in a community garden so naturally I never saw them when they
sleep but I have read that some bees like to rest in soil and leaves.
Maybe someone else will post with more information.

Since Lars mentioned some types of bees I went to googles image gallery
and I found these:

http://www.pestproducts.com/images/bumble-carpenter.jpg

http://www.govlink.org/.../house/images/bumblebee.jpg

Maybe these pictures will help.