After the Deadline checks English spelling, misused words, style, and grammar using artificial intelligence and natural language processing. This add-on adds After the Deadline's smart technology to the Firefox browser. Now you can check grammar in your online word processor, spell check your Web mail, and send tweets with confidence.
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.