Proper caching for static resources

We do not use cache-control response headers for images (CSS, JS, etc.) properly. We only use the "Last-Modified" header and "Etag" (not sure, if this one has any impact).
This causes in particular IE (6 and 7) to perform requests for JS, CSS and image files to the server on each request (with "if-modified-since"). The server responds almost in all cases with "304" (Not Modified). It does not stress the bandwidth greatly, because no content is sent as a response (only HTTP code 304 and headers), but the server gets more requests, as it is normally needed. For example, the home page of our demo site (in the live mode for guest user) results in 22 resource requests and only 2 of them receive non-304 response (all others get 304 - Not Modified).

I will try to use our "Set Header Filter" to set cache parameters for (at least part of our static resources) properly. Let's see what it will bring.