A company I worked for once took a call from a school. They rang to tell us that a pupil with a pacemaker felt unwell whenever he used a computer that we had supplied. Boy did that put the wind up the directors! A team was dispatched and they found that the problem was cause by emissions from the computer monitor. The monitor met all current EMC standards (or at least thats what the labels said) and lucky for us it wasn't one we had supplied. We gave them one of ours and last I heard this fixed the problem. It's easy to be complacent about EMC until you have an incdent like this.
Recently I read a report that suggested mobile phones are capable of corrupting the content of computer memory devices (specifically EEPROM or battery backed CMOS RAM). The report indicated that this was thought to have been the cause of an aircraft crash (Ok it was a model aircraft crash but I had you going there!).