In order to manage MongoDB databases easily, Genghis, a single-file, self-hosted and web-based solution is pretty handy. It can be installed either as a Ruby gem or as a standalone PHP script.
Maplace.js is a jQuery plugin that simplifies integrating Google Maps into websites. It works with the latest Google Maps API (v3) and has methods for adding markers + custom content and drawing paths, polygons or routes.
Spectrum is a jQuery colorpicker plugin that probably comes with all the features you are looking for. It is image-free (only CSS and JS) and can be used for all browsers or only as a polyfill for the input[type=color] of HTML5.
Koken is a free and self-hosted CMS (PHP-MySQL) that is focused on building websites where portfolio/gallery is in the core (like designer or photographer sites).
Typeahead.js for building smart auto-complete form fields comes as a jQuery plugin, shows suggestion as-users-type and can feature top suggestions with the help of styling.
BugKick is an open source bug tracking and task management application (source is hosted on GitHub) that is “light” in means of features (which i sometimes nice).