 Which idea irritates you because it has not been taken far enough?
jrockway: Functional programming.I really like it when my computer crashes because someone decided that checking whether or not "-5435" was a valid array index was "too time consuming".  Wait, I hate that.  I have 4 cores that are idle 99% of the time.  Let the computer do some self-checks that will keep my data intact.(Read the ext3 source code some time and tell yourself that you trust important data to it.  The only reason it works at all is because everyone has already been burned by the most obvious bugs.)