The shirts I got at Eurogamer Expo 2011. The important bit is the front, so I made sure to take a picture of just the logo/graphic. From top-to-down:
1. id Software shirt I got for attending the 20 Years of id Software developer session.
2. Uncharted 3 shirt I got for scanning the QR code on the billboard at the entrance
3. CS:GO shirt I got from Valve for playing CS:GO. I got three of these, each for every day I played it.
4. A knitted symbol on the side of the CS:GO shirt.
5. OnLive shirt I got from the OnLive stand.
The Uncharted shirt is very comfortable and feels great, plus it's the least-branded -- only the sleeve part has "Uncharted 3: Drake's Deception" written on it. I've yet to try the CS:GO shirt but the texture feels great so I'm pretty confident it'll fit well. Same goes for the OnLive shirt. Sadly, the id Software shirt is much more snug-fit than the rest, despite them all being the same size. It's a bit tight.