I've made a parser and then extended it into a simple programming language, called Omicron.
If someone wants to test it and give me some feedback, it'd be great.
I've put the (still small and inadequate) documentation out on the net at http://www.strandmark.com/omicron.shtml
The language curently supports:
*Definition of new operators
*Built-in mathematical operations (derive, eq solver)
*Most C++ operators
* ^ (power) operator
*Run-time user input
One big, big drawback is of course: SPEED. But one can't get everything...
There's also an online compiler at the page above. However, it does not handle the 'input' keyword, for obvious reasons.