Even worse, your data might get scalded. If you've ever experienced corrupted files, power surges may have been the culprit. Why the power company can't supply steady, even power is beyond me to comprehend. Although I know a bit about electronics I don't know anything about power generation and distribution. Surges however, are a real problem that effect anyone with a computer or other expensive, sensitive piece of electronic equipment.
Lightning obviously can fry computers and other household equipment.
I've experienced several computers wiped out by lightning. Small power surges are a more insidious menace. They can corrupt data and ruin components but they can also slowly cause cumulative wear and tear as your hard drive slows down and speeds up due to uneven power supply. After plugging it in everything worked as usual and I couldn't even tell it was hooked up until I cranked up my laser printer at which point everything went kerblooey. If I had read the manual I would have realized that laser printers draw a bit too much juice for the small, personal UPS system I was using.