mod_entropy
As you've probably noticed if you've poked around here at all, I am uniformly terrible at updating things here. The 'last modified' tag provides a bit of feedback, but it doesn't differentiate between pages that are unmodified because they're perfect and unmodified because I'm lazy...
mod_entropy (not necessarily an Apache module) would attempt to tackle this in two ways. The first would be some sort of heuristic combining last modified and how often I view the page myself and maybe how often non-search engine hits. Therefore a page that I create, save, and then never update or use (e.g. many of these Ideas) would have a higher entropy than the front page, which I rarely update but which doesn't really have a lot to be updated.
The second part would then be a fancy (and probably annoying) way of depicting this entropy. Basically, programatically increase the noise in the returned page commensurate with the computed entropy. Add typos. Break img links. Draw 'noise' on a floating CSS layer. etc. Then have the page correct itself somehow over a few seconds so as not to be totally annoying.