I already know how to extend the number of digital pins on an Arduino using a multiplexer.
I want to increase the number of analog input channels that I have. One solution is to add another Arduino as a slave.
How would I increase the number of analog input channels? (I assume some MUXing and ADCs are involved). If it's too complicated to write in an answer, a general outline of circuit/code would be fine as well.
I am also open to shield suggestions, though I'd prefer it if there was a not-too-hard hardware solution.