I mostly agree about XKCD. Though I did not find (http://achewood.com/index.php?date=09232002) very funny. I will never let my family down by programming in Java.
The problem with Achewood, and why it's never been a hit, is that you have to read from the first comic to really get into it. The humor is character-driven and very rich, and you don't get any of that without starting from the beginning. But in six panels it's making four or five jokes, which is pretty astounding.
His nerd jokes were occasionally actually really good. When they weren't, they came across with the air of "Fuck you, I'm not putting these comics online for you." Occasionally he'd hit upon a nice riff with his heartbreak comics, too, and his whimsical outlook towards life was a lot more sincere and less forced. Then he homogenized, began repeating joke concepts, and started spitting out a lot of derivative work, with only the occasional truly clever idea. It's never gotten worse than mediocre, but it's very frequently mediocre.
I guess what I'm trying to say is all of you should read Achewood instead. The nerd jokes are better (http://achewood.com/index.php?date=09232002), it's funnier than any comic I've ever read (it's the comic that topped Calvin and Hobbes after seventeen years on the top of my list), and it's a real start-up, selling monthly premium updates rather than relying on any advertising whatsoever.