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.
SHEF is an HTML editing framework and component for the Java Swing GUI library. It can be plugged into the javax.swing.JEditorPane text component, adding usable HTML WYSIWYG editing capabilities. In addition, it works around various JEditorPane quirks and adds functionality currently missing from the standard Swing text implementation. It includes an HTML source editor with syntax highlighting, context-sensitive Swing actions, unlimited undo/redo, table creation and editing, click+drag resizable tables, and click+drag resizable images. It is easily embeddable in Swing applications or applets.