Doesn't it have something to do with the Brownies, as in junior Girl Guides, getting points for doing good deeds? In order to earn their badges of merit, I think. Only saying this as brother of a former Brownie, so ...
That's my guess too, yarb. But it always makes me think of brownies, as in the delightful baked product. (mmm... brownies...) I prefer thinking that my hours and hours of serving others will result in—instead of some embroidered cloth patch that would be ironed onto some dumb sash—delicious chocolaty goodness.
I was a Brownie for a brief period, and I've always associated brownie points with the doing of good deeds generally. It went with the Brownie Guide law: A Brownie Guide thinks of others before herself and does a good turn every day. (Not to mention the motto: Lend a hand.)
The badges were another matter and very much skills based, so you might earn a badge for demonstrating an active skill such as map reading, or a creative skill such as dancing, or a domestic skill such as knowing how to wash and dry cutlery correctly (I jest not, and this may explain the "brief period" of my membership).
F, you're my hero! I was talking to someone about my own guiding years the other day and the ceremony that surrounded being sworn in. I can still recite the pledge and whatnot, but I couldn't remember the Guide Law. It's been frustrating me for weeks!
I actually have about 5 camping badges, because in my small country town, there wasn't much else we could do.
I was turfed out of the Girl Guides when I was eleven.