I have a SPOT that I've used since April. I love it. So does my wife, who likes to keep track of me when I'm riding alone. The unit is basically a transponder that you can use in four modes: "Send 'OK' Messages," "Send Tracking Messages," "Send HELP Messages," and "Send 911 Message." See the SPOT website for explanations.
You can also publish to those of your choosing a link to a Google-based map showing where you are on your current trip or any other trip of your choosing. It's a great way to keep those at home up to date on your whereabouts, as well as documenting your travels.
I like the ability to send for help or a 911, even when in remote areas, as the system is satellite-based. You can even purchase insurance for helicopter rescue for a reasonable price as well.
If you travel a lot alone and especially in remote areas with little cell service, SPOT is for you.
I understand that SPOT has also released a smaller version, but on a cycle, that would not make a big difference; save the money and get the original, unless you just want the latest and greatest.
Check out SPOT at:
http://www.findmespot.com/en/
