Fairly recently I have picked up a very useful web service framework, Jersey (JAX-RS aka jsr-311; and its rock start implementation), and a nifty validation library Hibernate Validator ("Bean Validation API", jsr-303).
Both of these jsrs are relative new-comers, which makes me wonder what else I may be missing -- given that there are hundreds of JSRs, with various level of progress, activity and potential, it is not easy to track them all.
So beyond 2 I have mentioned, what else do others consider promising and worth paying attention to?