A couple of things that I would love to see
I'm looking for a few web services that don't seem to exist yet. First, a way to save my Twitter favorites to Instapaper (or similar services). Second, a webhook that sends content to Instapaper, as I dislike relying on third-party app integrations. Finally, a service that sends full RSS feed content directly to my email inbox in near real-time using pubsubhubbub. Existing services only send partial archives. If I can't find these, I might build them as open-source projects.