Unshelved
Unshelved is penned by Gene Aubaum, the pen-name for a real writer/librarian, and cartoonist Bill Barnes. Together they have published a webcomic nearly everyday since 2002. They were so good at it that they were able to make a book out of it.
Since I discovered them about a year ago, I've read it nearly everyday online. More than Garfield. More than Peanuts. More than Get Fuzzy.
I guess I can't say that non-librarians can get all of the in-jokes. But I tend to think that it is kind of like Dilbert in that anyone who works in an office and deals with the public can appreciate the humor.
I bought the Pimp my Bookcart t-shirt and it was much the conversation piece during Mardi Gras this year. Actually, there was some controversy among libraries about using the word 'pimp' as a verb. Personally, I like it.
I enjoy the Sunday book club feature. You never realize how absurd a book seems until someone illustrates the basic premise.
My local library has copies of the Unshelved books. I think they're there to educate the patrons. Or at least shame them into behaving.