Some notes about how different browsers implement disk cache

Konqueror

{{{
kdelibs/kioslave/http/http_cache_cleaner.cpp
kdelibs/kioslave/http/http.cpp
}}}

Cache is stored in "~/.kde/cache-katherline/http/[0-9a-z]/"

The top level directories are the first letter in the host and is historical when processing a lot of files in one dir was harder.

Each file is stored by itself.  So the file http://www.reddit.com/static/aupmod.png goes in: r/www.reddit.com_static_aupmod.png_2cd5ba49 
Each file: "host"_"file"_"fullUrlHash"

Each file contains the following (minus the text before each : so the first line is just '7') 
{{{
Version: 7
url: http://www.reddit.com/static/aupmod.png
Creation date: 1213180806
Expire date: 1213765446
ETag: 1207334405.0-334
Last Modified: Fri, 04 Apr 2008 18:40:05 GMT
File: <all contents>
}}}

In KDE 4 the file is gzip'd for 90% savings
Also r/www.reddit.com_static_aupmod.png_2cd5ba49_freq contains the number of times the url has been requested in a fashion that is not lock safe a has a bunch of problems.  Not something I would recomend copying

A seperate application goes through cleaning the cache removing oldest first.

A very simple system.

FireFox:
{{{
mozilla/netwerk/cache/src/*
}}}

A detailed article on extracting information from the FireFox cache, a good overview: http://www.securityfocus.com/print/infocus/1832

Chrome
http://sites.google.com/a/chromium.org/dev/developers/design-documents/disk-cache