Showcase is a Mozilla Firefox plugin that allows tabs and windows to be managed by showing them as thumbnails in a single window, tab, or sidebar. It includes a find bar that will filter the thumbnails and the capability to select the thumbnails in the same way you would select files in your system.
ff3sudoku is an add-on that features an engine for playing Sudoku puzzles. It can generate random puzzles, but it also detects and imports Sudokus from several Web sites, including websudoku.com, sudokupuzz.com, sudoku.com.au, and others. There is also a stand-alone version working in Firefox 3+ and GoogleChrome.
ABPlayer is a video player developed with the Flex 3/4 SDK. It allows users to post comments onto the playing timeline while playing online video. Comments are scrolled across the screen when the video reaches the timeline position of the comment, allowing interactive and realtime commenting on the video. It also features bottom, top, positioned, and reverse scroll options which allow users to create closed captioning and subtitles for videos. Comments support color, font, size, transitions, movements, 3D transforms, and opacity.