DNA isn't just a code, it's the ultimate information - the data without which the ability to perceive data wouldn't exist. We now have the ability to write our own messages into this biological blueprint, but there are important factors to consider before you start scribbling cellular graffiti.

The human genome contains about three quarters of a gigabyte of data, and it's pretty unflattering to find out that the "How to make YOU" instruction manual is less than a quarter of the size of an X-Men: Wolverine DVD. (But don't worry - the real "you" in your head is, even by the simplest estimate, at least seventy terabytes). Scientists have so far inserted the equation of relativity, their own names and even Latin poetry into the "junk" DNA of bacteria and plants.

Which is an extremely dangerous sentence: the idea of "junk" DNA is an extremely popular misconception which leaps from "we don't know what it does" to "it doesn't do anything." Research teams are continually discovering regions of "junk" which turned out to do something vital after all, almost as if it was unlikely we'd be saddled with 97% of our genomes doing nothing. We can confirm that regions of it don't seem to code for proteins or instructions, but until someone builds an organism without all the extra code we'll have to assume it's doing something. Or even better, try using the "extra" storage space for something else and let us know what happens.

The idea of encoding information in DNA is so spectacularly sci-fi that people can't help but come up with crazy applications - which is awesome. That's exactly what science should do! People want to record evolutionary archives of our innovations, coding cockroaches to carry our knowledge past any future catastrophes, while others only want to trademark their genetic innovations (an unsettling and unfortunately far more likely outcome), but the fact remains that DNA is still a terrible place to put information - if only because any species which could extract it knows at least as much as we do anyway.

Some say we should search our own selves for messages from extra-terrestrials, encoded messages from the alien creators of the human race. But the facts are:
1) Beware any idea that was actually used as a Star Trek plot once

2) The "aliens made us" theory is better suited to late-night radio talk shows

3) It could still be true, but if it is we'll find any such messages in the course of regular, real research into the code instead of hunting for a message
In fact, it's essential we don't start searching for scrawls inside our cells, because with seven hundred and fifty megabytes of data there'll be such a fantastic Nostradamus factor (finding messages in random garbage once you've already decided to) that anything identified will be an artifact of the observer.

A real application of genetic information is the idea of genetic computation - the idea of encoding a problem in DNA and evolving a solution. Obviously there's an immense amount of work in setting up such a computation (not only encoding the information, but designing a situation in which solving the problem is beneficial to the organism), but that's okay because it's only intended for use in otherwise "insoluble" problems - quandaries where the analytic methods fail and the computation time is longer than the expected endurance of the sun.

Evolution, after all, came up with things butterflies, pilot fish and duck-billed platypii - if anyone can come up with unexpected answers, it's nature. The great unkown is: will DNA and the ability to encrypt communication prove to be a constant throughout the Universe?