Have you ever caused an outage on a big website by accident?(as an user)

No Repercussion, but yes I was beta testing an interface, using it normally, the company must of been testing it live publically, and it was connected to their production database.. I was testing the edit user feature, and all I can say I believe the code was a little messed up and lacking a few "Where" statements... Short Version my profile edit: My testing "Mr. Andersoned" the whole person details/user tables..

Don't believe I have.

> Did they notice?

If they didn't they aren't doing their job.

> What were the repercussions?

If a user can cause an outage on a website through normal non-malicious use there should be no repercussions for the user. A website should defend itself from common user mistakes. If it doesn't then fhe website is buggy. Of course, this doesn't include clueless governors getting upset at someone viewing the page source.