If someone made a really intuitive web app for this I would totally use it. Usability would be key though. Painless to enter data, easy tagging system, and easy wandering system to keep on top of everything.
Making an intuitive app would be half the problem. The other half is finding enough customers to pay for it - there is no obvious way to segment and/or target users, other that a single life-hacker post that you're going to get.
Make it free for users and work out how to monetize the aggregate data (sell it to Google?) somehow
Here is my app. Needs some more work on the really intuitive part: http://flashcarddb.com
looks like the '90s
How about some more constructive criticism?
make buttons bigger and use more shiny colors. Better yet: get a designer.
I tried this. It failed due to lack of revenue. I was trying an ad-supported model.
My problem would be trusting all of this information to a third party. At the very least, I would want a means of exporting the information in some open format to my desktop.