Finally got a chance to work on my #Steam library tracking app.
It already does something I haven't seen anywhere else: of course it can sync my games, playtime, achievements via the Steam API, but also link this to my actual spending via CSV import. (I've been keeping a spreadsheet for years).
So now I can see which of my games have the best and worst $/hr, total spend by developer, publisher, or genre, $ per month/year; basically anything. It's really cool!