The iPad, even to Apple, is an undefined product with no real purpose. People get all up in arms defending their precious iPad's, but in all reality, everything on the iPad could be done on your computer or iPhone. The best argument that people have for their iPad's are for ease of use. Sure, you could go online on your computer, but it's so much simpler to just have a small device laying around... with a larger screen than an iPhone. Simplicity and ease of use are its strong suits, and apps like Popplet are going to make the iPad the revolutionary product that it is destined to be.
Popplet is a web-based mind mapping application that lets you visually collaborate with other Popplet users. It can collect documents, pictures, videos, and text, all in a nice an organized way. Check out the Popplet video to see just how it works.
The Popplet iPad app still seems to be in a beta-like stage and does not include some key features of the web service such as the ability to collaborate between multiple users and a web version to access the data elsewhere (apparently it was originally made in Flash... whoops), but it is, in its current stage, a great personal idea mapping app. Once the collaboration features are live, Popplet could be one of the most useful iPad apps out there. Pick up the full version anytime, or check out the lite version for free to see if you like it.