Me. I've always felt that one of the most important things you can do in software development (as well as other areas of life) is just admit when you've made a mistake. Especially if you can laugh at it, at least a little. The bigger the mistake, the more important it becomes to ensure that you can fix it and go on.
Last week, I made that mistake. I deleted a database at my hosting provider that was on a SQL Server 2000 instance. Thinking that with the newer version of the application software I was running, I had certainly migrated my databases to the 2005 instance, I blindly deleted the SQL 2000 database. This had the effect of killing two of my public web sites. As in Gone. I didn't back them up. No history. The backups that I have are too old to be useful.
The odd thing with this is that when it comes to working with clients, I preach and practice good backups. Nobody gets to click DELETE until we're sure we can recover from what we're about to do. I'm incredibly meticulous, and very aware of what's about to happen. To others.
Lesson: Be more cognizant of the enviroments. Verify the facts (a la connection settings) prior to performing maintenance tasks. Even if it's your own stuff.
Lesson learned. Now off to rebuild a couple of web sites. At least I'll get to I'll have to redo them the way I want.