"I'm trying to be completely self-sufficient in my approach to biking. That means using my legs to generate not only motion, but all the juice needed to power lights, computer, GPS, radio, cellphone, laptop or tablet, and anything else I might add down the line."
You can definitely some something to power some of this stuff, but if you expect to be able to power all of it - if I understand you correctly - you are just being unrealistic.
As someone else mentioned, you can get a Luxos U headlight with usb charger. This will power the front light when you need it, or while the front light is not on it will provide usb power to charge 1 other device.
But that's as much power as you're going to get out of it. Anything that doesn't have a usb charger is going to be difficult if not impossible to charge (I don't know if it can be done or not). And anything that does get charged via usb, you'll only be able to charge 1 thing at a time.
I don't know if there are other options, but a regular dynamo hub generator just doesn't put out that much power. It's plenty of power to charge a cell phone (and you can use the gps on your cell phone as your gps). I don't think it's actually enough power to charge a tablet. It's really not enough power to charge a battery for a light like the Dinotte XML-3, or an actual laptop.
Are you looking for something you could ride your bike at night on to produce power? I just think you're being overoptimistic about how much power you can produce on a bike...