So, I like data. I love charts and graphs and maps, and keeping track of things, and quantifying and analyzing. If you called me part of the quantified self contingent, you wouldn't be terribly off-base. As evidenced by things such as MapThing.
I've been GPS tracking myself pretty much constantly since I got my first smartphone back in 2011. That's a lot of data, and there aren't a lot of good tools to wade through and revisit that kind of constant stream of GPS data - most of the tools I've seen are focused on individual runs or trips or hikes or what have you. And of course, I have lots of ideas for things to do and analyze, and like controlling my own data, so I built an app of my own.
So far it's only for my own use - I don't even run it on a VPS yet, it just runs off my home computer - but it does the essentials: lets me look through all my GPS history, drill down to a given date or area, and see where I was at any given time, and if I want, replay my travels. I also want to integrate my Foursquare/Swarm checkins, and layer extra data and analysis on top of it - I've started grouping stops into "Locations", and splitting the GPS data into trips. It's functional, but there's a lot more to add moving forward.