Big Ball of Mud is a fun read, and I recommend it heartily to anyone who hasn't yet been involved in a Very Big Project, or to anyone who has, and is looking for insight into why the project turned into a big mess.

Big Ball of Mud has its roots in Ralph Johnson's group at the University of Illinois, Urbana. (Johnson is one of authors of Design Patterns.) A lot of very influential thinking sprang from the circle that formed around Johnson. (One of his grad students implemented the first Refactoring Browser for Smalltalk.) Refactoring in turn formed one of the core practices of Extreme Programming.

The references in Big Ball of Mud are worth mining for other good reading. There's also a Big Ball of Mud page on Wiki that has some extra words by Brian Foote, plus a few good pointers.