An open platform for science on Amazon Mechanical Turk.
Participants recruited via Mechanical Turk first interact with your task via ads. Ads are simply the digital version of hanging a poster or flyer around your university building in order to recruit participants. Technically, ads are snippets of HTML code that describe what your task is about and what you're offering for compensation. As a result, they are the front line for any subject recruitment online. It's easy to overlook the importance of a good ad, and making that ad visible to as many participants as possible.
The psiTurk Ad Server is a cloud-based solution for delivering ads to participants securely, while providing experimenters useful information about who is taking their experiment, where they are connecting from, and possibly what other experiments they have completed.