Io is a prototype-based programming language inspired by Smalltalk (all values are objects, all messages are dynamic), Self (prototype-based), NewtonScript (differential inheritance), Act1 (actors and futures for concurrency), LISP (code is a runtime inspectable/modifiable tree) and Lua (small, embeddable).
small vm (~10K semicolons)
multi-state (multiple VMs in same process)
incremental collector, weak links
actor-based concurrency, coroutines
64bit clean C99 implementation
embeddable, exceptions, unicode