In a new study out today, doctors have shown that the little magnets in the headphones and earbuds often used by mp3 players can actually have some effect on pacemakers when placed with about an inch of them -- or, directly over where the device was implanted near the heart. Users of mp3 players who have a pacemakers are being warned not to place the buds into a shirt pocket or drap them around their necks while resting. Normal use of earbugs and headphones does not pose any additional risk.

This is pretty scary news so keep it in mind when you're out shopping or picking out your most-wanted mp3 player. For a list of some of the hottest mp3 players for the holiday season, check out this comprehensive one compiled by our friends at Digital Trends.