If there's one thing that users of David Allen's Getting Things Done (GTD) system suffer from, it's typically the temptation to mess with their system. Nothing feels better than having all of your stuff under control, except maybe having all of your stuff under control in a sexy new system.

So if you've been rocking the same GTD application for too long and feel it's time to mix things up a little, check out this amazing survey of the GTD application landscape at About This Particular Mac.

While it originates at a Mac-centric site, the list should be of interest to any GTD practitioner since many (if not most) of the listed applications are web apps, with the occasional cross-platform app thrown in.

For good measure, here are our favorite GTD apps based on platfrom:

Windows: ClearContext (an Outlook add-in)
Mac: iGTD
Web: Backpack or Remember The Milk