Huh. I just noticed that the font that Safari uses for scottstuff uses lower-case numerals. That is to say, a 1 is the same height as a lower-case letter, not a capital letter, and some digits (4, 5, 7, at least) have decenders, just like the lower-case letters j, p, and q.
Kinda cool. I haven't noticed a lot of mainstream fonts with lower-case numbers before.