I've written a copy (call it a homage) of Regex Coach.
It allows you to play around with Java regular expressions, as defined at http://java.sun.com/j2se/1.5.0/docs/api/java/util/regex/Pattern.html and I can run it on my Mac and debian boxes.
It implements only the _very basics_ of Edi Weitz wonderful Regex Coach, allowing you to enter a regex and observe the hilighted matches (including captured groups).
Obviously the original tool is much more functionally complete :-)
screenshot: http://javanicus.com/groovy/groovy-regex-coach.gif
You can download the full source from this link http://tinyurl.com/2bf8v9
And to run, install groovy: http://groovy.codehaus.org/Installing+Groovy
and use this at command line: groovy RegexCoach
Edi, I hope this homage is respectful of your excellent tool which I use all the time when I have a windows box handy.
Cheers
Jez