Love this idea, and the copywriting on the page is absolutely brilliant!

I hand-rolled my own solution a while back on my own server, simply creating a random forwarder and "tagging" it with a description, so I can always go back and lookup what fw839kopa4 was for... It's a ugly hack, but works.

My ugly hack has the added benefit of not accepting just any email address, but only those I explicitly defined. On the flip side, I have to run this small script and can't just give out citibank.myname@mydomain.com to anyone on the fly.