Mozart/Oz is very nice. In many ways, it's a "more functional" (excuse the pun) Concurrent Prolog. It's multiparadigm, although it seems somewhat stuck in academia compared to other languages like Haskell and OCaml, which have branched out more. For anyone interested in both using Mozart/Oz and learning a novel way to think about programming language paradigms, I highly recommend "Concepts, Techniques, and Models of Computer Programming" which uses Mozart/Oz to implement kernel languages of other programming languages, and which is written by key Mozart/Oz designer-developers.