When I travel I often use earplugs at night (E.A.R foam are my preferred brand) to mute the sounds of strange places and get a good night's sleep. Only problem is, the pathetic "eep eep" sound of a typical travel alarm cannot penetrate the earplugs. For years I have searched for a truly heavy-duty portable alarm, and finally found a good candidate at the Petro Truck Stop in Kingman, Arizona: The Screaming Meanie.
Also available from online sources, the Screaming Meanie is not a clock. It is a countdown timer. You set the number of hours and minutes between now and the time you want to wake up. You can also set the volume, either to "loud" or "frighteningly loud." In case 110 decibels is not enough ("loud enough to wake the dead!"), they have a 220 decibel version too!
When you start the Screaming Meanie the alarm is ON by default. This eliminates my habit of waking up five or six times just to check whether I set my travel alarm correctly. You just know this thing is going to work. You can't possibly sleep through it because while the 10 and 5-minute warnings can be turned off with one button, it takes 3 buttons pushed simultaneously to silence the final alarm. My only quibble is that it should be smaller (it is a rounded plastic block, 1″ by 2.25″ by 5.25″) but hey, it was designed for truckers. — Charles Platt
Screaming Meanie ($25)