One of the places we regularly visit has a tree that houses gnomes:
Lucia knocks on the door every time we go by, but alas, we always come by on market day, and the gnomes are never home:
We have a pine tree in our back yard that would be a perfect residence for gnomes. We've sent out the word. The housing market is difficult right now, and so far, there have been no inquiries about the property. However, I feel confident that we shall have gnomes take up residence in our pine tree before the summer is over. Gnomes make excellent neighbors. They weed gardens and water the plants.
June 2015 update: We finally have a door in our tree. For those of you looking for fairy and gnome doors, visit Nothin' But Wood.