I am looking for a good introduction to non-uniform computation, sometimes known as computation with advice.
"Good" being relative, I'd like something that gave me a high-level understanding of what's known (and what's known to be difficult!) as well as some historical perspective, without getting bogged into too much formalism - while at the same time giving me pointers to places where I can find all the details. I have a reasonable grasp of elementary theory of computation and the very basic complexity classes, but don't expect me to know e.g. that ZPP = RP $\cap$ co−RP.
Any suggestions? Bonus points if it's an introduction that's freely accessible in digital format.