I've had sessions of more than 5 hours, but that's having sex 4-5 times in that amount of time and that includes all oral, foreplay, etc plus making a sandwich in between sometimes.
With my girl now it depends on the mood - Sat night we were both loaded and very frisky and got down to business and it was over in 20 minutes. If I want to take my time it can be over an hour from the first making out to the final bit. Then again if she wants to give me a quicky in the morning and gives me a good BJ it's over in minutes.
Shortest ever I have no idea - quickies can last five minutes.