Campfire is a popular web-based project management system for teams - I've used it before and will use it again. It's so chock-full of Web 2.0 goodness that I'm fairly sure you need to wear horn-rimmed glasses in order to get it working properly, but I digress. The good news it they've just released an iPhone version of the system -- a version that will automatically appear when you access your Campfire account via your iPhone.
So now instead of leaving the guilt and shame of not keeping up with all your work projects on your desk, you can carry it around in your pocket. I recommend your shirt pocket, because that's closest to your heart, where you guilt belongs.