Thanks for the reply, ppe. With regard to what I'm thinking of, it would be a browser of all documents that were sent to any or all of your email accounts - basically an attachment browser. The attachments wouldn't be on the kindle, just metadata. When you wanted to read an document it would then get sent to the kindle.
You could look at "all Word documents" or "all documents sent to me by Frank Smith", or just do a keyword search. It basically would open up all the documents in your email history to your kindle. Big chunk of server work there as well as the kindle app, so it'd be nice to know somebody else would use it. So far not looking so good.