With The Watchmen movie debut just around the corner - it's time to look at that fabulously strange branch of DC Comics known as Vertigo.
Vertigo is DC's line of comics intended for mature readers. Interestingly, although the plots and situations are occasionally sexual in nature, more often they are just deeply psychological, taboo, and/or disturbing.
The line's crown jewel was probably Sandman - created by Neil Gaiman (who also wrote the current film Coraline). I used to read a lot of Sandman, Doom Patrol, and a few other Vertigo titles. Unlike say, Fantastic Four, these are often challenging reads - because they play with your expectations of what comics should be about. (Don't expect any clearly defined heroes and villains).
Today, I discovered that Vertigo has the first issues of several of their most popular titles available online for free (in PDF format). Sandman, Books of Magic, Doom Patrol, Preacher, Transmetropolitan, Army@Love (above), and many more.