Go into the list of hits you did for that day, look for their name and click on it. It'll open up a messaging page.
Click on the name of the hit to see more info, then on the bottom right you will see contact requester.
Can do 15 of these, says good bonus! 5000+ Title: Estimate height and weight of people (bonuses available) Requester: MSRNE researchers [A1F9W6UY3YL34J] (TO) Description: Quick and fun: Estimate how tall and heavy forty people are Reward: $0.40 Qualifications: Total approved HITs is not less than 5000, HIT approval rate (%) is not less than 99, Location is US Link: https://www.mturk.com/mturk/preview?groupId=25M5K4F0OHOY6WPF5DF2U92HFJ212D [size=-2]Powered by non-amazonian script monkeys [/size]