I just built an engineering calculator web app for a competition with a deadline this Friday.
It's designed to be intuitive and fun; and you can share your solutions, conversions with the outside world. I was hoping there'd be some interest here. And maybe if anybody uses it, they can provide feedback. I'd love to get it as clean as possible for the competition. I'm hoping it's already pretty "clean" but robot engineer feedback would sure be nice.
It's free and will remain available forever. It uses html5 localstorage so it works offline too.
app landing page:http://www.tigerbaby.me/robot-maker-calculator