TWiki - should use CSS, also it would be cool to translate to XML instead of HTML and use a style sheet to transform. That would make it easier to write stuff in Twiki and move it to DocBook XML. Also, it would be cool to have a twiki plug-in that could automagically produce image galleries out of directories full of image files (i.e. thumbnails, etc).

Dia - UML shapes need a once-over. Add more attachment points, allow different colors, etc.