Another pleasant (if woefully late) discovery: jQuery
I admit it: I am generally a late adopter of new things. It has its benefits -- I have missed countless train wrecks by waiting for others to figure out god awful messes hidden in well-intended APIs, libraries, patterns, styles and wherever such dangers lurk. But downside is also obvious -- I could have been more productive had a found gems in cases where they hadn't been hidden for months or years.
This is the case with jQuery.
What a pleasant awe-inspiring library: compact, powerful, intuitive and
straight-forward to use. I suspect there's no point in elaborating more
as to why I like it -- most everything has already been said. Just
google for testimonials.
All I can say is that I wish I had dug in earlier.
But better late than never.
And on a related note another obvious observation ("Hey, this is Captain Obvious calling... ") is that JAX-RS (Jersey) and jQuery go together very nicely; especially when using Jackson-based JSON binding.