How about making food flavored packets of juice, for all the bulimic chicks out there... Breakfast, lunch and dinner, all under 2 calories!
You could use it to make tiny cups of hot tea or coffee?
Swap out the blue/red/amber LED for a UV LED, and use it to detect counterfeit money!
Poker-communication! (Or a bad tell.)
Ever search for night-crawlers?
Vampire detector? (Using the UV light again.)
Rock concert salute... since you no-longer have a lighter...
Fire-fly (Lighting-bug), attractor... Trust me, you can trigger a whole field of blinking light, with just one puff!
Baby-magic-trick... it will amuse a 1-year-old for hours!
Use it in the bedroom, instead of a safe-word... It is more fun in the dark!
Try it with your wife/husband too!
Glowing farts! (Wait, it works when you inhale... never-mind... try it backwards!)
Walk around all day, with two of them, and convince everyone you are a modem or a network card, and can only communicate with those two flashing lights...
Put two, end to end, with the lights on opposite sides... Put one light in your mouth, while the other is on the far end... suck and blow, or breath through it... looks like you are playing light-pong... the end lights up, then the side in your mouth, then the end, then your mouth...
Don't try that with the farting thing... unless you are into that kind of kinky stuff.
Lie and tell your astrology students that it is a laser-pointer... have them try to find the dot in the planetarium star display on the ceiling...