Ask HN: Has anyone here run a contest before?

I'm doing some pre-launch marketing for a project that won't be complete for another couple months. In addition to a typical content marketing strategy, I want to try running a simple giveaway contest with the goal of building a mailing list and eventually a community around the startup.

I know I'm not the first person to try this so I'd love to hear from anyone who's already gone down this path. Here's a few questions that I'm sure anyone else thinking of running a contest would find useful.

What startup was your contest for? What did you give away? How did you get the word out? How long did it run for? What were the results?

Our contest is for a project called Shadenut (http://shadenut.com). It's an app to help professional and DIY mechanics look up the technical details of any car. I'm think of giving away a fancy torque wrench[1] since it's something that every person in our market needs and will put to good use.

I'll be sure to recap the details of my own contest here when it's complete.

[1] https://store.snapon.com/TechAngle-174-Models-Ratcheting-Flex-Head-Torque-Wrench-Electronic-TechAngle-174-Flex-Ratchet-12-5-to-250-ft-lbs-1-2-drive-P760213.aspx