Lojban

Lojban is a constructed language. Its grammar is based on the principles of logic. The syntax is unambiguous, but you can still semantically be ambiguous if you want. You can express complex emotions or attitudes too. Learning Lojban is intellectually stimulating.

http://en.wikipedia.org/wiki/Lojban
http://www.lojban.org/

Haven't we already tried that with Esperanto? Cause last time I heard of Esperanto it was an incident on an imaginary spaceship in a fiction book.