For extreme conditions look to the Oil & Gas Industry. The tools they drop into wells are rated -40 C to 175 C. That is operating temperature. The tools have to work at that temperature for 8, 12, or even 20 hours without failure. TI is developing a line of high reliability microcontrollers that are rated to 205 C.

When I was an undergrad at Southern Illinois University several student started a website (siunightlife.com) I think and the school shut time down.