There are lots of tools to help you learn new things or build better habits, but Persevy is the first one we've seen leverage the power of the Pomodoro productivity method to get you there. Choose something you want to learn (or add it yourself), then let the tool guide you through the work sessions to master it.
If you don't find anything you want to do, you can always add your own, and build a structure around it that fits the Pomodoro Technique. You can add specific milestones, or activities you want to accomplish in each Pomodoro (25-minute working session). If 25 minutes isn't the right time for the things you plan to do, you can customise the Pomodoros to suit your goal. From there, it's just a matter of repeating your pomodoros, pushing further in your activities, and eventually -- after 10,000 hours of practice (not factual, but the guideline that Persevy uses) -- become a master at it.
You can use the site as a simple Pomodoro timer if you prefer, but signing up and adding your own personal skill "quests" will unlock its real power. Hit the link below to try it out, or walk through the site's interactive tour.