Beware: The browser may handle unclosed tags just fine, but many times your markup goes through a library first, and libraries vary in their support. For example, I found I had to close my tags when writing HTML in jQuery templates, and I found a bug in Zepto the other day with creating HTML from a string containing multiple self-closing tags (a similar practice).
After being bit those few times, I've gone back to closing all my tags (even when the w3 spec says unclosed is more correct). If I'm going to have to do it sometimes, I'd rather be consistent and do it all the time.
I've run a TRUNCATE in production by accident thinking I was logged into the dev system. I truncated the 4 core user / transaction tables. I've never felt the blood drain from my body so quickly.
Good old binary logs and an office floor to sleep on. I make copies of the data whenever deleting or truncating now. I think we all have to do something ridiculously stupid to start taking precautions.
