REST Services that will return current date/time in JSON for any registered time zone. Seems pretty straightforward and easy to use.
A protocol for timestamping arbitrary stuff and storing it in the Bitcoin blockchain for posterity. Can be used for arbitrary data, by default documents dragged and dropped into the webpage. Easy to verify, too. Public submission servers exist. Proof of concept implementations in Python, Javascript, and Ruby. Seems kinda gimmicky, to be honest, but a use might emerge later.
An on-line web application that shows you what time it is in every other time zone around the world relative to the current time. Handy if you're trying to figure out if you should ping someone at a particular hour.