I noticed that there is a Steam thread created already, but it wasn't created for this purpose (more of a discussion about it thread). Theres threads for gamertags and such for everything else, why not start one for the Steam users on the PC!
The threads purpose is for people to kind of group up and playing some games together. There is no requirement to post your Steam name (like having to have L4D or something), and there is no official games that we only have to play. Just add, chat, and game :D
Without further ado, I shall start with mine.Steam Name: Balverine_the_pimp
(Don't ask.. this was made years ago, and Balverine was taken D:)(The name you post will be your login name (yes, the account one). Steam has the system setup like this so you don't try to add say "Andrew" and have to search through 50,000 other Andrews for that one correct one. I know its a bit lame but thats how it works, and at least it does :P)
Or, you could always post your Steam Page if you are uncomfortable with posting your login name.
Example: http://steamcommunity.com/id/Balverine(If you want, you can just copy my example for my page, and just delete the part that has "Balverine" and put your steam pages ID there also. Note: Its not your steam name either, since it can be a separate thing. ((Name could be Applesauce while the page ID could be Oranges))