Use permalink structure to pass variables

I’d like to pass extra (predefined) parameters to a WordPress page via the permalink structure. Sort of like the http://www.mysite.com/blog/post-name/page/2/ structure, but with other parameters than ‘page’.
I’ve been looking at parse_request() and I guess I could modify that function, but I’d rather like to use a plugin or some other method that doesn’t require core hacking. The Permalink plugins I’ve found don’t seem to solve my question.
I’m willing to pay for development of a plugin that does this.