I’ve made up a new word. I googled it and I’ve checked the urban dictionary, and I don’t see it mentioned anywhere. So here it is: nerditia.
It is just what it sounds like: a militia-like group of nerds, or an organized group of nerds. Here is an example: “Tipped off by Slashdot that there was a free-after-mail-in-rebate TiVo + satellite dish + dishwasher + star wars dvd box set combo on sale, the nerditia descended upon Fry’s Electronics and stripped it bare.”