[vosper]

By far the most effective alarm clock I've ever used is Alarm Clock Xtreme for Android. The killer feature is the math problems functionality, whereby you cannot disable the alarm, short of removing the battery, until you've solved math problems at your chosen difficulty.

Solving 5 relatively simple problems like "17 * 12 - 34" gets my brain going like no other alarm - I am fully alert by the end of it. My mental arithmetic has gotten better too :)

There are also tons of other configuration options in the app.

[robjama]

That was actually the original idea. To use math questions as an alarm style but we opted to go with the Shake to wake option to get people moving in the morning. Plus it's more tactile and goes well with the other alarm styles of slapping the phone to snooze and flipping the phone over to turn off alarms.