http://math.hws.edu/javanotes/

This looks like an interesting AJax framework: to check out: http://qooxdoo.sourceforge.net/.

http://www.javaworld.com/javaworld/jw-06-2004/jw-0614-equals.html - Correctly implementing hashcode and equals.

http://itext.sourceforge.net/tutorial/general/webapp/ - Neatly explains how to take the output a servlet and generate a PDF dynamically.

http://www.onjava.com/pub/a/onjava/excerpt/jebp_3/index2.html

Example 3-8: The magic spell to disable caching

// Set to expire far in the past.
res.setHeader("Expires", "Sat, 6 May 1995 12:00:00 GMT");

// Set standard HTTP/1.1 no-cache headers.
res.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");

// Set IE extended HTTP/1.1 no-cache headers (use addHeader).
res.addHeader("Cache-Control", "post-check=0, pre-check=0");

// Set standard HTTP/1.0 no-cache header.
res.setHeader("Pragma", "no-cache");

http://javapathfinder.sourceforge.net/

From their webpage: The answer used to be simple: "JPF is an explicit state software model checker for Java bytecode". Today, JPF is a swiss army knife for all sort of runtime based verification purposes.

If you are not familiar with formal methods, this basically means JPF is a Java virtual machine that executes your program not just once (like a normal VM), but theoretically in all possible ways, checking for property violations like deadlocks or unhandled exceptions along all potential execution paths. If it finds an error, JPF reports the whole execution that leads to it. Unlike a normal debugger, JPF keeps track of every step how it got to the defect.

http://www.randelshofer.ch/oop/javasplash/javasplash.html - How to create a fast splash screen.