You know, there are bio-hacks that come along once in a while that are really worth mentioning. In true geek-it fashion, an aspiring 'entrepreneur' (among other things) has developed a portable, miniature health monitor that uses a pretty advanced assembly of chips -- from accelerometers to Bluetooth to flash storage -- in order to display health information from an electrode wearer in real time.
How does it do this? Why, it sends the information gleaned from the electrode-wearing subject directly to a Bluetooth-enabled Windows Smartphone (running a small application), which provides a real-time ECG readout in addition to other health telemetry data.
No need for a hospital visit with this contraption, which if put into a single unit would be no bigger than a small cellphone. It's powered by a small Lithium-Ion battery with attached voltage regulator. This is obviously a prototype, but it's a pretty finished product all things considered except packaging it up into a casing of some type.
See the YouTube video below and I think you'll agree -- this is one of the neater DIY creations in the field of self-geeketry that's made it to my YouTube viewing yet. Very cool -- check it out.