Okay, it's not a mousetrap; it's an alarm clock.
I have a problem with oversleeping. I think this makes me uniquely qualified to build an alarm clock, because I know what would work to help me wake up at a reasonable time.
The alarm clock I have now is far from perfect, but there's some stuff about it that I like. One good thing about it is that it was free. I won it as a door prize at a New Year's party I attended to ring in 1994, which makes it over ten years old. The alarm sound is nice and loud, which is good. Actually, it's so loud that it's been known to scare roommates and various sleeping companions over the years (I, on the other hand, have been known to let it go off for minutes at a time before becoming aware of it). It has two alarm settings, meaning you can set it to go off at two different times if you're so inclined.
One thing has always bothered me about alarm clocks. Let's say you have your alarm set for 8:00, but for some reason you need to get up the next day at 7:50. On most alarm clocks, you can't just set it back ten minutes; you have to move it ahead eleven hours and fifty minutes. That's a little tedious. I don't think it would be too much to ask for an alarm clock to have the ability to go forwards and backwards. Four buttons: H+, H-, M+, M-. Is that too difficult? Also, I don't want to have to hold down an "Alarm" button to see and adjust the alarm time. Too often it becomes a test of manual dexterity, trying to hold down that button while pushing the others to set the time. There should just be a switch to flip over to "Alarm."
My current alarm clock isn't too far from that. You do flip a switch for the alarm setting mode. It has three setting buttons: fast forward, forward, and reverse. Just minutes, no hours. If the alarm is set for 6:39 (my usual setting) and it needs to be set for 8:00, I have to hold down "forward" (or "fast forward") until it advances those 81 minutes. This setup would be acceptable as well as my other suggestion, but there also needs to be a fast reverse button.
Now let's talk about the snooze button. I have a love/hate relationship with the snooze button. On one hand, it's heaven to be able to slap at the clock and then just roll over for a few more minutes. However, I have a tendency to use it too many times per morning, which is generally why I get out of bed later than I intend. The snooze function on my clock is only for seven minutes, which is excruciatingly short. A perfect alarm clock, I think, would allow you to set your own custom snooze timer. I'd set mine for about half an hour, and hopefully only hit it once per day.
The best thing for a perfect alarm clock would be if it came equipped with little legs so it could get up and run around when it goes off, along with screaming its head off. If I had to get up and chase it down each morning, I think that would help a lot.