Allow RegExp matching

It would be great if we could use regexp (even with some limitations) to match the string to be replaced, and allow for substring substitution.

For example, it could be used it to replace each occurrence of
"Bug#([0-9]+)"
with
"http://myhost/bugzilla/show_bug.cgi?id=\1".

Very handy for intranets.
What do you think?
Mau