I sure do! I use Evernote, which is an app. I can use it on my computer(s), iPad and iPhone. I can clip videos (my own, how tos, etc.), Fenzi class sessions and more.
I don't tend to get too fancy for field stuff. I just take notes after lessons and practice -- what went well, what did not, my mistakes, what to work on, etc.
For obedience, I keep it organized by exercise and I typically check in after a private lesson.