Yeah, I know, you're probably getting sick of these Automator services. But I really do create a new one of these practically every day to make my life a little easier, and maybe some of these will be useful to others.
This one puts a UTC timestamp on the clipboard. The timestamp is an ISO 8601-format string like "2009-11-09T13:14:03Z". If you'd like a different format, type "man date" in Terminal to see how to change the output format of the date command in the shell script below.
