Hello! I'm the lead developer of a new computing mod for Minecraft called Modular Computing. It adds high-quality emulated computers with a very fast CPU core, custom assembler, lots of peripherals (planned, we already have a few though) and many, many features.
The main features of the mod so far:
Efficiently emulated CPUs (should be able to run about 500-700 per server at once without major lag) with a custom assembly language
Terminals with Unicode support and a 256-color palette, letting you be far more expressive than with ASCII alone
Paper tape, manually editable, readable with bundled cables and readable/writable with both ComputerCraft and Modular Computing computers!
Musicboxes that play tunes depending on paper tape data - useful even if you can't program!
Hardware Echo puts an end to typing lag by typing the characters on the client side as soon as you type them!
Fully open-source! It also comes with a vibrant development community.
More storage tiers
Direct audio playback via cassette tapes
Proper software for the CPUs (so far we only have a Monitor)
Graphics cards, courtesy of ds84182 - the author of CCLights2!
NOTE: If you want documentation, this is the wrong place. Go to #moducomp on irc.esper.net - the mod is mostly intended for the fearless and the risk takers.