For a number of years now, this is one of the few email notifications I have and the only one for a webcomic.
Piled Higher and Deeper, aka PhD Comics. PhD Comics is a very funny take on life in graduate school. The characters in the strips appear in short episodic bursts, dealing with work, friends, money, parents, expectations and of course their professors.
The characters in strip are well drawn, and perfectly relateable. Cecilia, is a geek, and a girl. Both very important in understanding her. She can be neurotic and brilliant, and did I mention neurotic. Mike Slackenerny has been around for a long time. Even though he is the king of free food, and a (surprise) graduate, his wife Jen and their kid are desperately waiting for his doctoral brilliance to shine through.
Tajel is a firebrand, humanities student that has an opinion about everything and finds causes to protest passionately about. Finally, there is the nameless guy, that was the hero of the comic and has never, formally been named.
Finally, no post about PhD comics can be complete, without mentioning their most important motto - procrastination. And reading the comics from the beginning can definitely be a good way to attain it. Or you could just look through the most popular ones.