Hi all, wanted to give a heads up on a platform I am currently developing for playing games and generally improving your play (I certainly need to improve mine). It is called OpenGammon and is still in Beta. There currently aren't too many players, but if you come around the daily tournaments there usually is quite some activity going.
If you have comments or questions feel free to ask me here (or send an email). If you are interested I can post updates in this thread.
I second this! I've been playing on it and think it's one of the best-designed platforms. And there are constantly new features being added. The puzzle rush is especially fun.
I worked the last couple of weeks on implementing a new feature I call insights. Insights make use of a position classifier to analyse your games and aggregate the positions into categories. I then compute for each category the lost equity and the error rate. You can browse your and other player's insights through the user detail page.
One feature that I added on top of insights is the ability to create user quizes. These are sets of 20 puzzles that focus around the worst categories of that user. So if you are bad at (for example) holding games, you can practice them by doing your personal quiz (you can also try other user's quizzes if you want).
Interesting. Out of curiosity, is your classifier based on analytical rules or learned? I feel like there is significant ambiguity and lack of formalism in the backgammon vernacular (which is understandable given how soft the concepts are). A good analytical classifier would provide precise definitions (interpretations?).
Analytical. You could do it with SVM's if you really wanted, but I think the "bunch of if's" method is the way to go (I made it slightly nicer than that, but nothing too fancy).
Happy to share the code/definitions of the tags if anyone is interested. Also more than happy to get suggestions and/or help with the definitions as I am not the strongest player myself.
I personally would very much love to see and discuss as much as you are willing to share! 
I have been working on OpenGammon again and added a couple of new features you would probably like. First are the Daily puzzles, it is basically a puzzle each day with an explanation by one of the daily puzzle editors. We try to pick a variety of positions such that it is helpful for players of all levels.
The second new feature is the Pip Rush. It is similar to puzzle rush, but now you have to count pips of a 'random' position to score points. Sounds dull? Yeah, it kind of is, but it is a great way to train your pip counting. Currently the all time high score is 12 (in 5 minutes).
There are many other small (and not so small) new features since last time I posted, so make sure to take a look. If you have questions or comments, feel free to let me know.
This sounds cool. I made a small desktop app that does similar using positions from various sources where the count might matter. How do you select your positions for this mode if you don't mind me asking.
For now it just picks a random puzzle from OG, so indeed the position might not be a position you want to count. I mostly made it for myself to practice. For now just getting my brain working on the arithmetic is (for me) the most important thing. It would indeed be nice to only take positions where a pip count is useful, but honestly, that might be hard to accomplish (I haven't looked too much into it).