A Modern USB keyboard, due to power needs and a sophisticated feature: Dynamic alteration of the symbols on each key. As well as a glowing key option (green/blue LED under the transparent board so all the keys are visible in the dark).
How it works:
Simply put there is a small LCD or similar
device under each key, which is used to show what each key's symbol is supposed to be. There is a Driver that controls what each key is supposed to be and look like. Say you need to change your keyboard from US standard to the European one, with special accent characters and other different symbols. This is easily accomplished from a Tray icon that lets you choose what type of layout it should be equal to. There are also Macro/Script buttons that the user can program with special functions and a few language buttons that allow fast switches to/from several commonly used keyboard layouts.
Also there could be a Miniature variant for Cellphones using the same technology, or PDA's/ Pagers... anything that needs to utilize a full set of symbols with a limited number of physical keys.
101+ -> 30 keys, by showing only a 'set' of keys at a time.
It simply shows the ones needed to type a message or even changes as you type the symbols, each key could change to a best guess of a word.