The xkcd Web site says it is “a webcomic of romance, sarcasm, math, and language.” It’s an interesting mix, for sure, but it’s also completely accurate in describing this webcomic that isn’t afraid to be a little bit geeky. And the comics posted on the site cycle through all four topics regularly, even combing them from time to time (such as attempting to explain love through square roots, cosines and fractions). It’s not the most sophisticated comic on the Web — all its characters are hand-drawn stick figures — but it tackles somewhat sophisticated topics in a lighthearted and comedic way. With a hint of existentialism, it manages to be a little bit hopeful and a little bit hopeless all at the same time. In a more tangible sense, xkcd’s greatness comes from its popularity among the Web-surfing crowd and its ability to go viral on sites like Digg on a regular basis, which is a difficult task given the crowded online comic scene today.