Still not sure what to do with an extra $20 other than to save it

I still have an extra $20 bill from last week, with no new great ideas for something productive to do with it. My default is to save it (and earn 3% interest), but I would prefer to find something to do with it that would have some more substantial, longer term impact than, say, paying my electric bill.

I would like to find something that would make some noticeable difference a year from now.

Maybe the simple fact is that $20 is small change these days. But  that begs the question of what I would do with an extra $200 or $2,000 or even $20,000.

Two ideas that come to mind are that maybe I could attend some professional training seminar or trade conference.

Maybe the real question is not the money or financial cost per se, but what can I productively do with my time, how can I more productively use an hour or two or day or two of my time for a more significant, longer-term gain.

-- Jack Krupansky