As a Beginner's I'm having trouble finding a sample DB on ..

I've just started digesting Yank's "Build your own DB-driven website
using PHP & MySQL' as I'm trying to prepare a dynamicly updated
interactive site for a charity which aims to link users to other users
whose needs are complimentary.

A totally different kind of p2p site!! Or is it? We think users could
search for what interested them which is being offered by previous
users.

I'm having truoble looking for an example DB similar to the target DB
required for my project. Where can I go for such example DBs?
Golive provides example DBs for photo album, sales catalogue, user
forum, shopping cart, e-magazine, and calendar. But I can't find
anything suitable.

I've thought of a shopping cart DB but dont thicnk it's close enough.

All suggestions greatfully accepted, Thanks. I have to start somewhere.