There don't seem to be any rebcode enabled versions of the REBOL interpreter for free download, but can you use rebcode with the SDK version of REBOL?
I'm doing some heavy number crunching and REBOL can be a little slow, I've noticed.
sunanda — 13-May-2011/13:46:45-7:00
I think the links here to older versions still work -- and the versions include rebcode:
http://www.rebol.org/aga-display-posts.r?post=r3wp389x2318