The book that inspired software patterns. I found it more interesting than GoF's "Design Patterns", and it feels less dated these days: The Timeless Way of Building by Christopher Alexander http://en.wikipedia.org/wiki/The_Timeless_Way_of_Building

The C2 wiki has interesting entries on software patterns and related ideas: http://c2.com/cgi/wiki?WikiPagesAboutWhatArePatterns

Stanford CS 240 has a great list of papers on system design: http://web.stanford.edu/class/cs240/

One paper that's no longer on that list, but I remember from when I took the class: End-to-end arguments in system design http://web.mit.edu/Saltzer/www/publications/endtoend/endtoen...