I often find that after I comment on a question, it's not as easy to get back to that question (or the comment i made) as it is to get to questions I've asked or actually answered. These are questions I'd like to help with but need more information. They should be easier to access, unless (most likely) there's already a way to and I just haven't come across it yet.
I just use my Activity page to keep track of questions I've commented on.
Click your name at the top, and then on the Activity tab. You can even narrow down your activity to just your comments.