For Scheme, I find that fcgi[1] does the trick: not only is it supported by Apache, lighttpd, etc., but you get state-preservation between requests; which is touted, for instance, as one of the benefits of continuation-based servers[2].
I've shied away from Scheme-based servers[3] hosted behind e.g. forward-proxies, because it seems to violate Occam's razor; but that's a personal bias.