I checked the database for this site today. As you can see there is not very much special things on this site. There is a couple of pages with information and a blog. When checking the size for it, I was stunned. The database file was over 600MB large!!!
So what will cause the database to grow that much? I started up my SQL Server Manager tool, and started to browse around the tables. The first thing I checked was the log tables and particulary EventLog table. There it was, over 74,000 rows with a lot of data in each row. It seems like the problem here is that the Event Log Viewer is logging everything by default, and it stores a lot of data. Clearing the log made the database shrunk to approx 10MB instead!
There is some valuable tips for this one:
1) On each installation, go to menu Admin->Event Viewer.
2)Go through all settings, see if you really need to log that much rows in your database.
3)Use the email feature, that will alert you when a serious error has occured. Although it seems that there is a bug in the DNN Core that spams the Event Log.
Hopefully this one is fixed in a newer version. As mentioned earlier, this is an installation that runs an old version.