displaying statistics on a website

In an attempt to grow my skills, and maybe learn a bit about php I would like to create or tinker with something similar to this:

http://morale.erikbenson.com/ or

I would like for data to be entered somehow and then displayed in a chart like this spiffy one: http://www.alistapart.com/d/accessibledata/example-timeline.html

I know this probably involves PHP and a mysql database - both things i want to learn alot more about.

I was wondering if there is actually anything out there like this already that is open source?

Thanks!