Yet another place to discuss and get ideas is David Allen's forum at davidco.com, which I signed up for yesterday:

For GTD methodology in general:
http://www.davidco.com/forum/forumdisplay.php?5-PUBLIC-Discuss-Getting-Things-Done

For GTD tools and software.
http://www.davidco.com/forum/forumdisplay.php?6-PUBLIC-Discuss-Gear-amp-Software-for-GTD