The second !

Imagine firefox, but as a website. I log on to firefox.com (imaginary) and get access to all my inboxes

I'm interested in this too.I was thinking of it more like an online Thunderbird.I couldn't find anything.

yes when i said firefox i meant thunderbird.

but really, any decent email app for mobile phone would do.

I'm not sure, but I think web browser are limited to talking http over the network, so you would need a proxy some where to allow for this -- architecturally similar to eg:

  http://engineering.linkedin.com/javascript/vncjs-how-build-javascript-vnc-client-24-hour-hackday

I've thought a bit about writing an email client (for the console, really -- but also thought about what would work on an Android phone) -- and I think making your own protocol and a server that proxies that protocol to imap/pop would be the way to go.

As far as I can tell this is how gmail works, and I seem to recall the original author of the SUP email client went in a similar direction on a new project (but I can't find the link atm).

I really don't like the idea of a "fan in" structure, where a proxy will end up knowing all usernames/passwords for every user's every email account. It would be better to have the "app" speak imap/pop -- but as I understand it -- implementing a useful subset of IMAP is not a trivial and makes ponies cry.