Data grapher plugin request

Hi Folks

I'd really love to see a plugin that can gather data that users can enter on a free/daily/weekly/monthly basis and show a graph of that accumulated data (similar to what the reports plugin does). Every user should be able to choose whether his graphs are public or private and he should be able to collect graphs for multiple topics.
(e.g. A user should be able to enter his or her weight every week and get a private or public page where a graph shows the trend of the weight curve. If the user likes he can add another graph and collect data for BMI, too. Or waistline circumference or whatever the user wants to track.)
There are plugins that can create graphs from blog posts, but this leads to only one graph per blog and you have to create a new blog post per data point.
What I need is a page where the user can choose which data to track, in which intervals to track and whether his data will be public or only be visible to him/other logged in user, and of course fields for data entry.

Anyone else who thinks that a plugin like this would be useful?

Mike