Do I need to pick a specialty?

I've always been a jack-of-all-trades. I've been equally comfortable working on my own automobile, digging with a backhoe, rapelling down a cliff, repairing an arcade monitor, working on math problems, writing software, installing Windows, performing electrical work on my home, installing a satellite dish, etc.

But, my career field (computer technology) has just exploded over the last decade, and I'm finding it overwhelming if not impossible to keep up on everything.

I'm not about to stop learning, but at what point do I need to stop knowing something about everything and start specializing in one or two things? How do I personally decide which technologies to specialize in? How do I ensure that I maximize my income while maintaining a high level of personal satisfaction?

BTW, I've come to understand a long time ago that I derive great satisfaction from prototyping (R&D). My productivity level at the beginning of a project during the problem-solving stage is so much higher than at the end of a project (when there's nothing left but tying up loose strings). How do I get someone to pay me just for this type of engineering while letting someone else finish and refine a project?