Guys, it might be a scam.
If you check at the bottom, it says: "© 2014 steam-cards.com All rights reserved. All trademarks are property of their respective owners in the US and other countries.
This website is not affiliated in any way with Valve Corporation or any of their partners. Steam is registred trademark of Valve Corporation.
This website and its services comes with absolutely no warranty."
EDIT: I reached 20 points, but it leads to a survey...
at least it's probably not harmful.