It's actually a very reasonable task. Inflation is much cheaper than deflation, so this should be less intensive than mod_gzip. And while YMMV, based upon the stats given by the maintainers of mod_gzip (and in my own experience) the vast majority of user-agents can handle zipped content-encoding just fine.

UPDATE: This should be rather easy as a handler, assuming content is zipped check to see if Accept-Encoding includes zip (or whatever the actual token is). If not use Archive::Zip or some such to inflate over the pipe on the fly.

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I'm not belgian but I play one on TV.