There are probably over 100 different manufacturers of microprocessors, each with 100 or more different chips.
EDN magazine publishes a "Microprocessor Directory" each year. Or did anyway. The most recent one I could find has dead links, but is still an interesting list of manufacturers: http://www.edn-europe.com/microdirectory.asp
Many modern microprocessors are not very friendly to the hobbyist or small scale manufacturing. That probably applies to most of the micros capable of connecting to the internet and playing video. Sometimes there are cheap, small, "development boards" that can be used if your main interest is software development or adding small amounts of hardware. "Chumby" and "BeagleBoard" are examples in this class.
For a interesting and philosophical look at some of the microprocessors around that ARE accessible to the hobbyist, check out my Instructable: