Here is a link to a US Chemical Safety Board video summarizing several recent lab accidents.  If you have never visited or heard of the CSB, here is a link to their web site. Have a look around.

This link is to the case CSB case Study of the Texas Tech explosion with nickel hydrazine perchlorate. It has a nice illustration of the Swiss Cheese Model of safety. This model was devised by British Psychologist James T. Reason at the University of Manchester in 1990.