Good Old Games is running a speed test where if you participate you could win a free game. Just log in to GoG and go to http://www.gog.com/downloads_quality
and run the test.
I didn't win anything but sounds like you can participate in it multiple times throughout the day. This is the message I got when complete:
"Unfortunately you did not win anything this time (yup, every participant has a chance to win a free game). Donít worry though, you can start the test once again in a few hours - we will get more data to analyze and you will get another chance to win the free game!