I put together a site over the last couple of months, writing mostly while commuting to work.
The idea is simple..people rate which kitten they think is the cutest.
I know, I know, it's been done a billion times before, but it seemed like a nice project.
http://www.kittenfaceoff.com/ At this time, 90% of those photos are taken from openphoto.net (a friend's site), so they have bizarre names because I lack creativity (A cat named Face Foot?)
If you're a nerd, it's written in PHP5 (completely OO), using MySQL 5 (master / slave replication (complete with a sync detection and wait for sync)), Smarty (Templating system), completely CSS (Not one table, anywhere), Imagemagick (thumbnail resizing).
I did something interesting, all binaries are stored on the DB. This way I can load balance the site without needing an NFS mount of anything like that. Instead of reading from the DB every time an image is requested, I wrote a file caching system. So each file is only requested once from the DB.
Also, once every 24 hours I do a complete mysqldump on the slave, so I have a backup of all the data incase of a server crash.
I know it's overkill, but that's what makes a project fun.