Starslip Crisis by Kris Straub. I never got his previous comics, but this one is just genius. If you go to read it, try not to read the latest stuff until you've caught up from the beginning - if you want, I have volumes 1 and 2 in print, available as loaners, if you prefer that form factor. It's the story of the first museum set up in a starship, and the curator/captain. The story transcends genre, skillfully balancing art appreciation humor with more straightforward sci-fi tropes. Just... go read it. I can't do it justice.
The Non-Adventures of Wonderella by Justin Pierce. Hilarious weekly sendup of an amoral second-generation superhero, and her friends. And her arch-enemies, of course.
Dinosaur Comics by Ryan North. The pics are always the same, and the words are always brilliant. And for a comic with such static visuals it has such a surprisingly rich cast of characters!