The older I get the tinier my 'purse' gets.
Now it's down to a little 4"x5" zipper pouch with a strap that I sling diagonally over one shoulder. I hitch my cell phone to it on the outside, and inside it carries cash, a chapstick, a few creditcards/ID/license, one folded blank check, my key, and a bag of my favorite jasmine tea.
If I'm just riding down the hill to breakfast on my bike, I sling it across my chest. (the strap tightens and loosens as needed). If I'm going on a longer ride I throw it in my saddlebag.
I originally bought it just for riding light on my bike, but I like it so much I use it all the time now.