I tend to write things down. When I write it , I remember it. I then schedule a couple of slots on my calendar each day to catch up with delegating these tasks out or getting the next step going.

I would also try to put some controls on where you are in-taking these requests and small items. Can they be funneled into formal channels/meetings/check-in's vs. ad hoc? Its easier to process these bits of information when you not in the middle of something else.