Okay, hardcore nerdery here. Sorry to the non-believers in the audience, but...
5. SMT technology for hobbyists.
Some will argue the point, looking back with nostalgia at the days when every IC was available in through-hole and sockets abounded, but I for one welcome our minuscule highly integrated overlords.
Ten years ago, when I bought my first parts from Digi-key, it was inconceivable to me that SMT parts could be usable on an at-home basis. Now, the proliferation of adapters (such as Capital Advanced Technologies' excellent "Surfboard" series), cheap hot-air and fine-point rework stations, excellent reflow tutorials, and extremely low-cost low quantity PCB fabrication services (like BatchPCB and the DorkbotPDX group buy), it's now completely and totally reasonable for a hobbyist to use SMT parts to realize extremely advanced designs in surprisingly small amounts of space.
All that's really needed is the right attitude.