I see potential for things like a share intent that would then let me decide what service (Facebook, Twitter, LinkedIn, G+) that I want to use instead of having a thousand buttons on a webpage that do the same thing. Look at the mess that AddThis is, just a huge list of sites to post to. Intents would be a way to avoid all the junk you don't use.
Intents for web could also be for retrieving content, or triggering video chats.
Just a couple off the top of my head.