Digital Deli: http://www.atariarchives.org/deli
Currently out of print, but I own an copy.
1. SCIP (Structure and Interpretation of Computer Programs)
2. Introduction to Algorithms (Cormen, Leiserson, Rivest, Stein)
3. The Art of Computer Programming (Vol 1-3).
4. Programming Pearls
For example, If you're doing Ruby on Rails, I'd focus on reading a solid book about Ruby and then one about Rails. A lot of people try to get good with a framework, without having a solid understanding of the language used.
Algorithms and data structures are a good solid requirement, but chances are you are doing CRUD / REST apps with a web framework and you need to master the framework and back-end language used first, before you dive deep into algorithms and the likes.
As a web developer understanding how the Internet stack and some specific protocols work, could very easily make your life easier.