Via LifeHacker I found this impressively huge collection of
Update: A while ago Gina (from Lifehacker) blogged about ThinkingRock -
not pretty, but their 4-color-striped GTD overview is impressive.
Update 2: My favorite GTD-tool is kGTD, based on OmniOutliner. The reason why I stick to this in favor of the clean-and-shiny stuff is simple: The outliner lets me add notes to entries and is extremly flexible in moving things around...