dont believe i have ever bought a game simply because we have a division for it, but I have bought games right when they come out (BC2) because we have a division for it.
otherwise I would probably wait for half-off sales, etc.
I bought DOD:S because when I joined, the only four games they offered were TF2, which I joined, DOD:S, CS:S (Which I have from the GOTY edition of Half Life 2) and COD4. I didn't have DOD:S and it was pretty cheap, so I bought it so I can join in on the fun. I still play it from time to time, but I'm still a TF2 person through and through.
I buy games I am interested in, not games that everyone in the clan is interested in.
I guess that isn't really fair though because I found out about team fortress 2 before it came out through eGO and then decided it looked awesome and bought the orange box. The fact we were going to create a division for it had no effect on my purchase though.
Technically I owned every game eGO has a division for('cept MW, Don't like it), but I suppose I did get BC2 mainly because I assumed eGO would get a division for it so I voted yes xD
I tried INS because I heard it talked about here. OMG! Did I get pwnd! My hat is off to you INS players, that's a rough game there. Looking at DoD:S & CS:S because they are dirt cheap on Steam right now. I would not have any interest in these games were it not for people in eGO talking about them. Also looking into BC2 because of all the positive feedback I read here. Am I buying these games because they are eGO supported? Not directly. However, were these games not eGO supported I would not be receiving all the free reviews I get from eGO members in these divisions. I also know that my first day on any of these games will be a lot easier because I know where to find servers where I will get help with my noob questions. And buying one of these games will allow me to play with more of my friends from the forums. I don't know of too many games that come with a built-in friends list like that.