Get in here
and enter your steam page (no need for password or anything, its completely safe).
mine, for example is http://steamcommunity.com/id/alonj
it will tell you how many games you own, and how much are they worth. if you have orange box, or any other pack, it will calculate each game separately, and it doesnt count the free mods.
i own 18 games, worth ~159$
it only sounds much, but a lot of these came in packages.