Project Idea:
PalmOS blog submitter. It's purpose is to allow you to write your own blogs on your palm and then upload them when you synchronize. Maybe it should keep the blog posts itself afterwards, I don't know.

Messages, a common format needed

To deal with gateways and other multiple views of the same messages, I think it's important to come up with an interoperable message format. There is the email type but I believe there should also be an XML based one and then specs on mapping that to other formats + metadata standards in the spec. Perhaps it could borrow some similarities with the Atom spec in terms of its metadata.