S9fES Reimagined is is a complete rewrite of most of the S9fES Scheme interpreter. The new interpreter is almost 100% compatible with the previous version. The main difference is that it is much faster.
http://t3x.org/s9fes-reimagined/index.html
I really like this guy.
Nils has been kicked out of school, has dropped out of job training and then out of university, and has quit a few well-paying jobs in technology (among others: for an IBM shop, a Linux startup, and a SAP contractor). However, the traits fostered in business and academia are simply not compatible with his values.