Just as Shaun suggested, I would use craigslist and backpage. I hire people all the time through craigslist under their domestic and labor gigs sections. You usually find people on there looking for quick work, and that want to be paid cash. Ill post ads with the subject as, "Easy $50" or "EA$Y MONEY" and will usually get a good response from that. I tell the promoters that I will pay them when the work is completed, which is easy to check up on, by randomly checking out the areas you told them to target.
my dad did this in the 60's and he would get me and a bunch of my buddies to go out on Sat and sunday mornings we got 1 cent per flyer we put out.
He also went to the local salvation army or were the bum's hung out and picked up 3 or 4 of them and paid them 10 to 20 bucks to walk door to door.. he had a loyal group in San Jose in the Day... not sure that works today ..but the kids work fine.