several vaguely related projects worked on by me: a 3d engine with a javascript-like scripting language (pdsys); an older scheme dialect (vmsys); ... (2009-04-28: I have been gone for years, may try to put up some newer stuff...).
A scheme interpreter written in C# for .NET/Mono. The focus is on embedability: the ability to add and customise scheme as a scripting language for new and existing .NET projects.
Features: R5RS implementation, embeddable, highly customisable.
HScheme is a Scheme interpreter written in Haskell, available as both interactive interpreter and extension library for other Haskell projects. Think 'Guile for Haskell'.