Scosche MyTrek Wireless Pulse Monitor

I have one, you get pick them up for really cheap on Amazon right now ($30)

The Mytrek was the first generation armband, and it has a bit of a flaw. If you read the reviews on Amazon you will find out about it, but basically it's not sweat proof and the sweat ruined them pretty quick ( Fixed this by having some electrical tape in my gym bag, so when I go to workout I put the tape over the charging terminals on the backside) so far so good, but I have only had it a few weeks.

You can't use it without your phone, it sends the info via bluetooth to your phone and your phone is what stores and processes the information. I don't use the Mytrek software, I use a APP called icardio and it works awesome (and it syncs with Myfitnesspal)