As long as I can remember, I've always enjoyed designing and building stuff. I have clear memories of building things with tinkertoy when I was around 3 years old, and as I grew up I made the usual progression through Lego, mechano, balsa wood models, electronics, software, ... The stuff you can build is limited only by the properties of the building materials, your skill level and knowledge, and your imagination. Well, wouldn't it be cool if you could build stuff out of molecules? If, through synthetic biology, you could craft some DNA to create the necessary infrastructure within a cell to create a tiny manufacturing plant for, say, carbon nanotubes? First thing to do when some far out idea like this pops into your head is to see if someone else has thought of it too (which is almost always the case). c.f.: http://ej.iop.org/links/q30/2N8tYInWNdqdYgCQ2+AZJg/nano5_1_R01.pdf As we become more adept at modifying proteins not just for binding but for catalysis, the nanotechnolog...
...neurobiology, molecular biology, nanotech, signal processing...