There is an absolute wealth of technical knowledge found in books out there, but nobody has time to read them all. What's on the top of your "must-read" list, either in your specific technology or in general?
I've got three.
First, The Little Schemer taught me how to think recursively more effectively than any other material I've read. You don't come out understanding recursive solutions to a set of problems, you come out equipped to tackle any problem at all recursively. It was a powerful experience, and a fun reading style.
Second, Programming in Scala, 3rd edition. This is a book about Scala but I learned a lot about programming in general from it and the author cleared up some misconceptions I'd held especially around closures. I didn't end up going on to use Scala much but this book made me a stronger programmer.
Finally, I've only just begun Mazes for Programmers but it's already a blast. It's both a nice reintroduction to Ruby and a super fun way to explore a bunch of algorithms. The subject matter is light and not academically presented but does not mean this book isn't absolutely packed with algorithmic goodness.
What else ya got?