Some folks generally have no problem getting out of bed when the alarm rings. These are the ones we refer to as "morning people." They are alert and productive in the mornings. Some don't even require alarm clocks, as they wake up naturally at around the same time every day.
On the other hand, there are those for whom the noise of the alarm clock is the most reviled sound of the day. Some may hit snooze until they are forced get out of bed in order to have enough time to shower and get to work. Others are heavy sleepers who may not wake up to the sound of a typical alarm clock. Those people must choose other, more hardcore methods. This is a list of alarm clocks for those in need of extreme measures to get them awake and moving.
The SingNShock clock, in the photo above, can be set up to actually give the user a shock when they touch the button to silence the alarm. Nothing wakes one up like being mildly electrocuted.
Whether it's a pleasant sensation designed to entice the sleeper out of bed or a much less agreeable experience like electric shock, see the variety of assured awakenings in the link above.