Here's a story from Inc. magazine titled "Email's Little Helpers." After getting past the extremely corny name, there is a decent listing of a handful of tools that are designed to make the email experience better in some way.

Among those listed are Xobni and ClearContext. I have beta versions of both of these tools and am trying to use them in my daily activities. I have a review of Xobni in process and will post it shortly.

Also mentioned are freebie file transfer service YouSendIt and one that I had not heard of called Reply to All Monitor. Love the name but not sure I'd shell out $14.95 to keep me from a mistaken reply all email. YouSendIt is further commoditizing the file transfer space by making transfers of up to 100MB free with fee-based services starting above that or for more "secure" (password protected) transmission.

Most of these tools are focused on enriching the inbox or mail client experience and I believe are not really getting at the core problem with email. They focus on making the existing approach more efficient through things like better search vs. getting at the root cause issues like volume and relevance.