There is another option for your consideration. BetterThanPants.com has T-shirts of all kinds. There are gamer references, old school (90's) references, PI references, Zombies, Star Wars.... You can browse to your hearts content through so many designs.
These shirts aren't some light cheaply pressed-on designs either. They will stand up to washings and wear. For my review I chose the Who's Your Daddy and Zombie Response Team shirts. (If you don't get the 'Who's Your Daddy' reference - you seriously need to watch Star Wars.) They are comfy cotton tees with cool nerdy sayings that announce to the world: I'm a NERD and PROUD of it! ;-)
Aside from these two as my top two favorites, I also enjoyed the Warning: If zombies chase us, I'm tripping you - Cool Zombie Shirt and the Diaper Loading Please Wait Baby Shirt.
Even better, is the fact that there are 3 web addresses that are all in the same company group. So check out http://www.betterthanpants.
com/, http://90stshirts.com/, and http://www.dailytees.com/. So many choices! Its like they say, "With shirts this awesome who needs pants?" You can also custom design a shirt for yourself or someone else to make it truly unique and special. Follow them on Facebook to see all their latest additions as well as deals http://www.facebook.com/betterthanpants or you can simply join their newsletter and receive email updates. Happy Nerd shopping!