Bulk action services to test load/parallel users

I am trying to find a good way to test my project in as real world a setting as possible. The general concept is that we'll have (hopefully) 1000+ users playing a synchronous game (sort of like HQ Trivia, if you remember that). I was wondering if there were any good services to hire a large number of people to execute a simple action to test load (will take suggestions for simulated load as well).

Thanks!