I've tried a few. I'm good at starting a timer but then always forget to stop it and end up getting a notification that I've been working on a 15 minute task for 22 hours non-stop.
I'm with Scott, if your company expects you to have specific skills for them and you didn't walk through the door with those skills, then they need to provide you paid time to acquire them. But your time is your time. Learn what you want to help you further your career.