For those not in the know Steam are currently running a promotion whereby every 2 days they set 4 objectives for users to complete. Every 2 days Steam will be giving away their top 5 wishlist items to 20 Steam members, each completed objective nets you an entry into the draw(so the more objectives you complete the greater your chance of winning).
The objectives involve either doing stuff for your Steam profile, gaining certain Steamworks achievements in certain games, or setting scores of a certain level on Steam Leaderboards for certain games. For most of the game-based objectives the games are heavily discounted for 2 days starting from when the objectives went live (after that you can still fulfil the objective, but the discount disappears).
To cap it all off everyone who completes any 10 objectives over the course of the promotion AND signs in to their profile on the 20th of December (no idea of the significance of that right now) is entered into a draw for the grand Treasure Prize of 100 free Steam games OF YOUR CHOICE.
Personally I had been thinking "meh, I'm not buying games just for a tiny chance to win more games", but I just noticed that there's a wee check box summary at the bottom of the page that shows your progression and I'm already up to 6, plus there's a pants L4D2 objective that'll bring me up to 7 (already have the game) so all of a sudden I'm thinking "I can do this!".
So who else is giving it a shot?
So far I have done:
1) Setup an Avatar
2) Have 10 friends on Steam
3) Play demo of "The Undergarden"
4) Joined an "Official Group"
5) Be a Devastator in "Magic: The Gathering" (this is the only one I've spent cash on so far, I have a friend who loves it and it was £3.49, and is actually pretty fun)
6) Send a gift to a friend (it must be counting historical gifts, ages ago I gifted someone excess HL2 and ep1 copies I had after buying The Orange Box)
and (potentially) 7) crass menagerie in L4D2 (easy, got it in the 360 version, bought PC version cus it was cheaper than buying 360 dlc)
So 3 more to 10 with 3 more sets of 4 to come.
If you've not been doing it so far you can still complete objectives from previous days.