I've blogged in the past about great "Wake Me Up At...." stickers which you can stick on your person and hope that some kind soul will wake you up at your Tube station, so you don't fall asleep & end up in Essex or Surrey or Middlesex or other ends of the line. Now the guys who've made them have branched out into badges for night buses:
In theory they're a good idea, but you're not at all as exposed when you're travelling on a bus. At most one other person is likely to see the badge, if they're sitting next to you and it's not like being on the row of seat on the Tube where at least five or six people sitting opposite you would be able to see you nodding off.
However, I do like the badge format for them rather than the stickers. They seem much more drool proof. The badges don't appear to be on the WakeMeUpAt site yet, so I'm guessing you can only get them in shops.
If you manage to grab a picture of someone wearing either a badge or a sticker, please let me know, as I'd love to see if they work. It would be interesting to see how long people have to travel wearing one.
Even something as in your face (quite literally) as the Japanese subway sleep mask didn't work. The passengers let the poor guy sleep on and never woke him. But with badges you look at less like a weirdo and less likely to be part of some art installation or "You've been framed" stunt.