these guys are trying: Residential & Commercial Trash Can Cleaning - Clean A Can trash can cleaning service
Seems like a hassle to start logistically but once it had momentum it could be really worth something.
2000 homes @ 2 cans per home 4000 cans x $2 $8000.
20 houses/hour = 40 cans an hour x$2 = $80 an hour.
100 hours to do 2000 homes.
If you had these accounts on 2 week cycles you could be grossing 16000 a month with some specialized equipment and two man crew.
These numbers are all just guesses, but the real question is how hard would it be to get 2000 homes within a short distance from each other to commit to a $8 per month invoice? If you could do this effectively through mailings, fliers and knocking on doors it would pay off.