Gmail?

"As part of Google's mission to organize the world's information and make it universally accessible and useful, we're testing an email service called Gmail.

Gmail is a free, search-based webmail service that includes more than 2,500 megabytes (2.5 gigabytes) of storage. The backbone of Gmail is a powerful Google search engine that quickly finds any message an account owner has ever sent or received. That means there's no need to file messages in order to find them again.

When Gmail displays an email, it automatically shows all the replies to that email as well, so users can view a message in the context of a conversation. There are no pop-ups or untargeted banner ads in Gmail, which places relevant text ads and links to related web pages adjacent to email messages."