What to make?

I need to make a program that connects to a database (or some kind of client-server relationship going on), grabs information, makes use of some classes (and inherited classes as well), and applies principles of polymorphism, etc. I'm not asking for help on how to make one but help on what to make. I thought about making a dictionary program but don't know how to use inheritence with that. I just need to make something for my job interview. I already know how to make this stuff but all of the stuff I've made in the past was implemented in Java or some other language. Any ideas?

guestbook, blog, poll

How exactly would I be able to apply inheritence with those? I can't see a way.

A title and an entry for a blog both share an is-a relationship with something like a cell in a table or an entry in your database.

Oh, so like you would make an object representing a table row and then the blog object would be a child of the row object?