A lot of appliances have reusable 8051-type microcontrollers - they are ubiquitous in monitors, TVs, white goods, car electronics, early harddrives and CDROM drives... and if you combine them with an external program memory (28F... series flash chips or 27C... series EPROMs are often suitable, and can be found in a lot of older computer scrap) and a means to write to it (specialized kit - build it or ebay it), they are an old-school but fun MCU platform. Almost all of the 40/68/84-Pin versions can be wired up in a way to use an external program memory, even if they are ROM or OTP devices.
Optical mice very often have an 68HCxx based reprogrammable MCU in them.
Also, always look for professional-grade, military, industrial control, or test equipment - these tend to use valuable, well documented generic ICs rather than application-specific parts.
Also, text-only, one to four line, monochrome alphanumeric LCD displays found in all kinds of equipment are often of the well-documented HD44780-like type. Forget about any LCD displays that work with custom segments (not very useful and difficult to drive), except such that are made to work with a voltmeter chip like ICL7106 usually found in the same equipment.