Prevayler – a completely in-memory data store, which operates extremely fast because it avoids object instantiation within J2EE. I had run across this last year at some point, but chalked it up as nonsense. Now that I hear Jot is running with it, it looks like i’ll have to take another look.

Laszlo, an XML-based schema et. al, for developing browser-based rich clients, has been open sourced under the GPL. Interesting stuff.