I'm amused by Google's mail Goggles
You may have seen the coverage on the BBC or elsewhere for Google's "Mail Goggles" - I stumbled across it when buying a coffee as Rory Cellan-Jones was discussing it live on TV. Apparently it's an "opt-in" service so shouldn't frustrate those of you who use their email service late at night and don't want to have your sobriety assessed.
I think many people have enough sense not to send emails (certainly after making the mistake once) while under the influence though can't help thinking it would be much more useful to have something similar for SMS messages or perhaps for prospective partner selection in night clubs!