I’ve just found two of the coolest web apps I’ve seen in a while. There’s a little-known facility in the HTTP standard that allows a client to connect to a server and stay connected (as opposed to most web browser transactions, which are of the form connect – request – download – disconnect). This has allowed several companies, most notably Google, to create map sites that start out at the country level and allow you to zoom right down to individual houses, downloading information from the server as required.
This same stay-connected functionality is what powers Google Select; when I was out in Stanford talking to the Knowledge Media Laboratory, we discussed using this to let users in learning landscape systems pick keywords more effectively, auto-suggesting common words as you type. I’m certainly looking into it.