Here's a language that +Mat Bettinson pointed out to me a few years ago. It's a highly dynamic programming language with some strong Lisp-like features (it's all executable data) leading very naturally to development of domain specific languages.

One thing that turned me off about it was the fact that it was a propitiatory language, which worries me a lot for vendor lock-in. While lock-in for other software such as office productivity suites are bad, it's still possible to migrate the contents to another format quite easily. Programs, on the other hand, are typically an investment of many hundreds or thousands of man-hours and have no simple way to port to a different language.

If I want to write a serious program I want to be sure that I'll still be able to run in another five or ten years from now. Thus I find it heartening that the developers of REBOL have chosen to continue development of the language in this direction.

Aww, I loved REBOL. I was drawn into it because the guy behind it was one of the leading lights of the Amiga's OS development. It was a real ground up redesign of a language with a batteries included feature set for web protocol. There have been various growing pains as they've struggled to commercialise it. 

I wondered off for Python in the end but I miss some of the stuff about REBOL, particularly the fact that you just used a single small exe to deliver most everything you need rather than the often nonsensical situation of Python installations.

The open source move seems to acknowledge that REBOL has stalled in activity. It's a shame that couldn't have happened years ago when that was fairly apparent... Not really sure it's going to make any difference though, sadly.