A similar thread has been made before but I think it's fun to see what others say.
You forgot all the really fun stuff in your list such as: ingiting matches, smokuing some black stuff, and generally atract attention on the street with your high tech toys
I wouldn't consider those things very "useful..."
Although... it is entertaining and impressive for someone who has never seen such a thing.
Normally I tend to avoid drawing attention "on the street." I actually only share my hobby with close friends, family, and the rare few that can appreciate it. I rarely use lasers in public and I
especially avoid showing teenagers.
This hobby is one that is very easily misunderstood. If you show the wrong people, you may be opening the door for someone who will eventually jump in the pool with the fools who make this hobby a dangerous one.
Also, I do not make a "public display" simply because I do not want to be lumped into the group along with the annoying kid at the movie theater with the laser pointer. Drawing the wrong attention can also land you some jail time, even if you know how to (and do) operate a laser safely. The average local policeman will likely know next to nothing about lasers, and to them, you will likely look like a "terrorist" thanks to the sensationalized laser "terrorist attacks."
Anglers arrested and DNA tested by anti-terror police for using laser pens to scare ducks | Mail Online
Maturity and self control are two items I believe are
mandatory for anyone who wields such a device. Unfortunately, the people who possess these qualities are few and far between.
I am very selective of my audience.
If you are asked what do you do with lasers (in a manner of statement: they are useless), you can pull out a comment of a kind: Same thing you do with your computer which you payed 10x more then my laser collection. Just helluva more fun (<- optional part)
My laser collection actually cost me more than 5 times as much as my computer. And that's not including blown diodes, broken drivers, tools, batteries, safety goggles, battery chargers, broken lasers, spare parts, lasers given away as gifts, accessories, etc...
Every one of us uses money for personal interests and hobbies. One would drink it up in a pub, buy a new graphics card for a computer, or buy some lasers.
No one can complain how your hobby is expensive when they themselves 'waste' money on a lotta things.
That is a good point-- one I often stress when someone asks me this question.
Everyone spends money on different hobbies for different reasons... for some reason, people understand buying 10 pairs of fancy running shoes more than building/buying a "few" awesome lasers.
So what do
I use my lasers for?
Well, for one, I love pointing out stars and constellations-- that pillar of light is just mesmerizing! ("Which star?" -- "THAT one!"
)
Illumination on camping trips (high power reds are great for preserving night vision),
Searching for fluorescent scorpions with near UV laser light (Awesome!),
Curing adhesives with near UV laser light,
Pointing out items of interest outdoors in daylight.
Some other uses could be:
Checking for counterfeit bills with a near UV laser, long distance signaling, a substitute for a flare, fishing lure, night vision illumination (IR laser)... Anything else?