Den Bagus has a writeup comparing four open source JavaScript frameworks, and I’d never heard of any of these.  Slightly embarrassing to say the least, but we’re all here to learn, right?  :)

The four he mentions are Ajax.org, UIZE, Ample and Hemlock.  I’ve just started looking at Ajax.org, and will give the others a look too – I’ve been in the market for some of this functionality recently, and was thinking I might have to resort to Flash or Silverlight for some of my needs.  Given what I’ve just seen at the Ajax.org demos page, I think there may be enough there to fit my needs nicely.

What are some other client-side JavaScript frameworks that you really love?