i know about analog multiplexing, also digital multiplexing etc. but the one thing i was wondering is, how many controls both for analog and digital could i fit onto the duemilanove using multiplexing?.
By using external multiplexing and digital shift registers there is no real limit on the number of things you can control. Think of some of the blinking LED cubes that are 10x10x10, that's 1,000 leds that can be commanded on or off!
Your real limit is most likely to be the internal RAM memory used to store variable information.
Lefty