$500.00USD. For an app. Interface that looks like the dev Googled all the images needed and used the first result. First line of the app store description is Do not buy this app unless you are a professional piano technician. Yet it's a highly powerful tool and professionals use it.
[1] https://itunes.apple.com/nz/app/tunelab-piano-tuner/id335568...
Meanwhile a single decent professional piano tuning app can sell for $500 (I don't know the sales numbers of course) with the most amateur-looking UI ever and a description that's a warning not to buy it.
Considering that most games get lost in the heap and sell basically nothing, maybe looking to see if there's some niche tool you could make instead isn't a bad idea.
Also just quickly recording things. Terminal block wiring inside the case of a VSD or other equipment (so when later you think 'oh wait, what was wired in to X5' you don't have to isolate the damn panel again to get in and check). Mark up drawings and take a photo to document it. Take a photo of that scribbled-over page of the manual that the client's been using for 10 years to configure their product and that's not recorded anywhere.
I wanted my Glass to help me with my business flow (namely, being on call at work), but it wasn't built to do things like... Connect to a non-Gmail account. And Google's requirement of uploading every photo I took meant I couldn't securely take work photos with it.
I have one of my best pictures of my chinchilla because of it though... Only way I've ever been able to hold something with two hands and take a picture.
Their products are full Android devices, as best i can tell.