Chess.com has a great openings database to explore, and it's definitely helped me a ton. The one thing I would really like is the ability to explore my own games the same way. It looks like the UI was actually built to support it, but I guess the backend devs at Chess.com decided that it would be memory-painful to also store everyone's games the same way they did the GM's.
So, I've begun writing my own standalone program that takes in the PGN files of your games, and allows you to traverse your games. So, for example, you can look at all of your games that began 1.e4 c5 2. Nf3 (and my program supports transpositions, which, wow, is kind of awkward to do). You could also filter by your or your opponent's elo levels, data ranges, color, time control, etc.
The end goal for me would be me supporting more advanced analysis (like which openings are most successful for me, where I'm struggling, recommendations for other openings, etc.). If you guys have other suggestions I'd love to hear them. I'm also willing to write a small chess engine down the line that could be used to support your game traversals.
Right now, I'm running all of this on the command line on my Linux machine. Fortunately, mostly everything is in java, so it would port hopefully very easily. But I would really need to get around to making some sort of UI for the user, because it isn't really practical typing in moves, and it doesn't look pretty.
If any of you would be interested in using this software, let me know! I haven't done any scale testing and, as admitted above, it's all on the command line, but I'm hoping to distribute something within the next month.
If any of you would be interested in contributing to this software, let me know, and I'll link you the github repository and we'll figure out permissions. Even if you don't have coding experience but still want to give input, you're totally welcome!
Lastly, if you're reading this and you work for chess.com, you guys looking to hire? I finish university next year and I think you guys would be cool to work for :).