Whatever you might think about Cell Phone Straps and charms, they are definitely useful for getting a hold of your cell phone. In fact, since a surprising number of people drop their cell phones in the toilet, maybe we'd all do well to have a system for hanging on to our phones.
I'm not into cutesy charms and leashes, but these Mobigrips ($10 each) might be just what I need. So discrete they disappear into your hand, all you do is unpeel the sticker on the circle of the grip, and stick it to your phone. Then each time you hold your phone, you simply thread a finger through the attached elastic, so if you get bumped or fall, you're still hanging onto your phone.
And it looks like it might be fun to fake people out with an "OH NO I dropped my phone!" bit.