I thought it was time I highlighted a smattering of useful and cool jQuery plugins. While there are many of these lists out there it's always nice to have new lists pop up to bring up the popularity of the best plugins. It can be hard to browse the master list and sometimes you dont see the coolest ones!
First and foremost I want to point out jQuery UI. If you aren't using it you're doing it wrong! It's a great place to start when looking for common javascript effects and widgets and themes.
And now in no particular order...
Labelify: Put text inside your text input boxes that disappears when you select the input.
Cycle Plugin: Transition effects for your divs (think Power Point slides).
ColorBox: UI dialog widget for modal windows. Check this out if jQuery UI's modal windows don't suit your needs. Great for image viewing.
Login Form Tutorial: Hidden form that slides in/out.
Table Sorter: Turn a normal table into sortable one!
Uniform: Themed form elements. Looks the same in all browsers.
50 (More) Amazing jQuery Examples