Just have a plugin like https://addons.mozilla.org/en-US/firefox/addon/bugmenot/ https://addons.mozilla.org/en-US/firefox/addon/bugmenot/ that works with http:/

Just have a plugin like https://addons.mozilla.org/en-US/firefox/addon/bugmenot/ https://addons.mozilla.org/en-US/firefox/addon/bugmenot/ that works with http://www.bugmenot.com http://www.bugmenot.com and instead of suggesting logins it suggests coupons. (add: in fact look at bottom of bugmenot -- retailmenot - wow, never knew about it: I wonder if it works well with the plugin) I don't know how the mechanics of the plugin are going to work but it'd do 3 things: suggest codes for the correct field, send used codes back and whether successful or not, also check whether used codes are already in database. Who supplies the codes? E-commerce sites to distribute a new coupon codes, and they could also tag certain fields for the plugin to suggest upon and tell it their coupon submit page. What happens if ecommerce sites don't actively participate: it doesn't matter people will give to get. In fact, there could be a karma system: supply a working coupon and get karma the more it is used. Use someone else's coupon and lose karma. The only hard bit is working out where a code must be entered and determining if it was successful - but sites don't change that much and that could be crowdsourced.