It's actually a myth that Harvey Mudd College only offers six majors. (It'd be a bit more accurate to say that there are only six departments. Of course, if you said that, you'd be making the same mistake most Mudders make in ignoring the fact that there's a Humanities and Social Sciences department.) There are at least three other majors: the joint major in math and computer science (all right, maybe that one doesn't count, since it's really just a combination of two others...), the IPS (short for individual program of study), and the OCM (or off-campus major). And yes, Mudders like TLAs.
People who major in IPS get to make up their major. Maybe this one doesn't count either, since most people make up something that's really just a mix of some other majors.
That does leave the last category, the off-campus majors. Since Mudd is only accredited to give Bachelor of Science degrees in spite of the fact that US News and World Report classifies it as a liberal arts college, this can lead to things such as getting a BS in music or art. However, because Mudd is part of the Claremont Colleges, Mudders can take any class from Claremont McKenna, Pitzer, Pomona, or Scripps as well as taking classes at Mudd, so it's well within the realm of possibilities to major in something that's not even offered on campus.
There are those who would claim that it's silly to major in something off-campus. After all, in order to graduate from Mudd you still need to take the Core, which includes two years of math, a year of frosh chem, a year and a half of physics (including a smattering of relativity and quantum mechanics as well as electromagnetics and mechanics), a semester of computer science, systems engineering and biology, and a couple of years of laboratory. Most people who decide to do a hum major transfer to one of the other schools by this point.
It's also not entirely true that Mudd's only reputation is for nerdiness. In spite of the fact that Pomona throws more money at parties, Mudd was well known at CMC and Scripps as throwing the best parties. (Mudders think this, too, but many Mudders don't actually walk off campus for social activities, so maybe their opinions shouldn't count here...) In fact, one year Playboy magazine voted North Dorm's Long Tall Glasses party one of the top ten college parties of the year.
An important part of life at Harvey Mudd College is the Honor Code. I've been to some colleges where the honor code was something you paid lip service to. At Mudd it's taken pretty seriously; in fact, the student body is pretty much self-governing.