Web Development kit all time favorite

i like a personal repository for my favorite frameworks and plugins.

bootstrap (aka Twitter Bootstrap 2, use bootswatch.com to get a good theme.
bootstrap.colorpicker (Color picker for Bootstrap)
bootstrap.datepicker (Date picker for Bootstrap)
jquery (A no brainer...)
jquery.chosen (Nicely style SELECT elements for easy filter)
jquery.noty (The best jquery notifications plugin out there)
jquery.qtip2 - Excellent Tooltip Library
jquery.tinycon - HTML5 Favicon Manipulation Library
jquery.mobile (Slowly becoming more stable, very neat stuff so far)
jquery.mobile.bootstrap.theme (A great theme for jquery mobile)
jquery.mobile.gmap - Responsive Google Maps for mobile devices
jquery-ui.bootstrap (The bootstrap theme for jquery UI)
jquery-ui.smoothness (A simple, clean theme for JQuery UI)
knockout (Knockout.js is simply amazing MVVM. Do their tutorial and you'll see why.)
sammy (Sammy is a small library that goes well with Knockout.js for handling RESTful eventful javascript)
FuelPHP (FuelPHP is the library I've settled on for doing my MVC and so far I've very impressed)

Update
99lime HTML KickStart HTML KickStart is an ultra–lean set of HTML5, CSS, and jQuery (javascript) files, layouts, and elements designed to give you a headstart and save you 10's of hours on your next web project.
Square UI Free Flat UI Free is made on the basis of Twitter Bootstrap in a stunning flat-style, and the kit also includes a PSD version for designers.