There is a company called iSafe which makes backpacks and laptop messenger bags with built-in alarms. They have now created a Waist Pack that does the same thing.
The iSafe Waist Pack is a fanny pack that weighs one pound when empty, and that includes the pack with an alarm and batteries. It has a wire that connects to a port, and if this wire is removed, there will be a loud alarm.
How loud is it? Let’s just put it this way: I was recently shipped an iSafe, and when I opened it, my daughter made the mistake of removing this trip-wire. The alarm was so loud, that it hurt my ears to be close to it.
I suppose if you are injured or mugged, that alarm will be enough to bring people running to help you. This is assuming that people don’t assume that someone else will take care of it. Considering how much I usually ignore car alarms, hopefully people will take notice of an iSafe alarm.
You should be able to get the iSafe Waist Pack on the official site for about $39.99. It comes in Black or Blue with Gray. If you want to take it on a plane, you had better use it in a real emergency, and expect a little more time with the TSA.