I'd really like to see more things built on top of email instead of using their own separate protocols (falling back graciously to email when possible).
Anyway, at this point it looks inevitable that I'll end up using 50 different apps/tools to do basically the same thing because everyone I talk to will use a different one...
I always thought SMTP would have been an interesting approach for sending out the equivalent of Web Hooks. Just email out XML or JSON, let it sit in email accounts and use POP/IMAP libraries to read.
It some ways it is superior to how web hooks are normally implemented. E.g. Most SMTP relays have queues for both inbound and outbound delivery. Plus there are semantics for failed or bounced delivery.
Hipchat is good at falling back to email only if you're not online; I'd like to see more similar services do the same thing. At the moment when something happens on facebook I get two notifications within a couple of seconds - one from the facebook app, then one from gmail.
If anyone is interested, I am working on a startup in this area (email+webooks). I'd love to see more thoughts on how email (both content of, and infrastructure around) can be extended and improved.
Anyway, at this point it looks inevitable that I'll end up using 50 different apps/tools to do basically the same thing because everyone I talk to will use a different one...