Some ideas...

Look through the stuff that came with your database software. Most databases come with some small database to use with example code or for testing purposes.

Write some code to use the XML interface to PerlMonks. Save the data you collect to a database you create from the information provided through the interface. This way you can sharpen your LWP/XML skills as well. Just make sure you keep the volume down or run at off-peak times.

Use another site's RSS feed as alternative to the above.