5) Bearmageddon: The scientifically credible prediction of the apocalypse caused by the rise of mutated grizzly bears who knock the human race off it's throne of superiority on Earth. Beautifully illustrated. Ridiculous plot line. I don't really know what else to say about it, just look at the title. It's awesome on an apocalyptic scale.
4) XKCD: XKCD is an almost unrelatablly witty comic. If I'm not mistaken it's run primarily by highly intellectual computer programmers and it shows in their work, aside from the fact that it features exclusively two-dimensional stick-figured when I'm sure the writers are more than capable of producing some amazing CGI characters. The jokes will often go over the head of the layman as this comic consists almost exclusively of inside jokes to the intelligentsia but some of them are legitimately hilarious and remind me to not take myself or my intellectual development too seriously. Some comics of theirs are even kind of serious and poignant and prompt some introspection which is interesting and rare for a web comic.
3) Yehuda Moon: Yehuda Moon is the story of a radically bearded bicycle zealot who co-owns a small, haunted bike shop called "The Kickstand." As a cyclist myself I can't help but adore this comic. It touches on so many aspects, both positive and negative, of the life of a cyclist and reminds me when I'm trying to fight my way through rain, snow, and wind that I'm not alone out there and that the spirit of Yehuda will always guide me. I can't tell you how often I've considered commuting in a car on a bad weather day and then thinking, "What would Yehuda do?" and then, with a grimace of pride, mounted my steel steed and charged into the tempest.