Hi guys! As I mentioned on previous contest I'm working on tool that predicts rating changes. I'm happy to present it now!
A huge amount of your nerve cells die every time when you wait for a rating update on Codeforces. Stop this! From now you could use this service, it calculates approximate rating changes for every contestant.
The most interested thing for you is extension. It partly modifies the contest standings page and shows approximate rating changes for every contestant. It is available for three browsers:
Extension in work:
Also you could find more detailed information (seed, rank, expected delta, etc.) here.
A project still in beta, so predictions are not very accurate. Average mistake around 5 points, but for the contestants at the back of standings it could be greater up to a few hundreds.
Prediction for todays contest (cf #399) is absolutely matching real rating changes! Thanks for riadwaw! He was close to find my bug in rating calculation:)