I had an Atari logo t-shirt when I was a teenager, but I bought it more for its rave appeal than its gaming appeal. I think it even glowed in the dark.

I might have had Ms. Pac-Man pajamas... I have a vague memory of Ms. Pac-Man being on something I used to wear.
Other than that, I can't recall having any other video game-related clothing. My kids have a few items, though. Derek has Mario Bros. pajamas, Wii pajamas, a Sonic the Hedgehog t-shirt, and a whole lot of Pokemon stuff. Vincent doesn't have anything, I don't think. He's still into Thomas the Tank Engine and hasn't gotten into video games much yet.