As my counterpart, Shinji, has done something like this before I thought I'd try it myself. As I started writing this well over a month ago I'm kind of glad I've only finished this now. As this post now seems well timed with the upcoming holidays.
Now for those adults out there who are well connected to there inner child, and those who just love anything geeky, here's a little run down of some cool geek merchandise (i know, wow, those two words in the same sentence). Keep in mind I'll be trying to update this particular post every so often, and no I'm not getting commission from these sites. But wouldn't a discount be a nice sentiment.
*Also I don't have any affiliation with these websites, just passing on what I assume to be cool merchandise and great gift ideas*
The first is an obvious choice, http://www.thinkgeek.com/. The name alone hints at what you'll find, from Jedi robes to organ transplant cooler. The website is extremely varied in terms of merchandise. Its definitely a place to go for those who have embraced their inner geek, as well as a great place to go shopping for people who are regularly hard to shop for. You have a game geek in the family get him an Ocarina. A star wars geek living in your basement get him a yoda plush. For the impossible to shop for shut in upstairs you can get a survival-kit-in-a-sardine-can. There's even something for that special lady in you life, pure-magic. The site is basically an ever growing stock of gift ideas for geeks and regular people of course. Though references may be lost on them. If your not completely sold on this site or not sure what to get out of all its awesome stock. Think back to an episode of Big Bang Theory in which Raj walks in to the comic shop blasting Darth Vader's theme music from his shirt, that's right its a real thing, enough said (link).
Another excellent choice would be http://sharkrobot.com/. Which is a site completely littered with internet and gaming references, countless web comic themed items, a number of art prints, and various t-shirt and hoody prints. Websites like VG cats, halolz, yugioh/team four star abridged, eddsworld, and harry partridge all have their merchandise on this website. It also contains some art prints and buttons for those who'll like to accessorise their cool hipster bags and rooms.
Now if you want a novelty t-shirt where the novelty doesn't diminish once you've bought it, bustedtees is the place to go. If you know about college humor you may already know about this website as they're the ones who started it.
Enjoy, and happy holidays from Blaku