http://www.purplemath.com/modules/ordering.htm - this is probably a useful reference for math problems. Although Level 1 might start with Arithmetic.

I'd also point out that your choice for physical basically requires access to a gym and knowledge of how to safely handle weights, which makes it (IMO) a really bad metric - I'd suggest something like "Hundred Pushups" and it's parent programs, or possibly a set of alternate tracks there. (My concern is primarily "requires a gym", which, no, seriously, not everyone has access to one of those, and even fewer people consider it worthwhile to spend money on)

"Running" a mile ought also properly be defined. Does a 16 minute mile count? I've generally seen a 10 minute mile as the slowest that's considered properly running, rather than just jogging, but that's "person who has been practising routinely for a few weeks."

It might also be a good idea to have a rough metric of how difficult a thing ought to be - is Level 1 "an average person could do this without practice"?

Last, I'll throw in my two cents that the memory requirement struck me as rather steep until I realised I have memorised "Still Alive", at ~275 words, without even trying. So there's an easy cheat mode for most people, I'd guess :) (I suck at memorising lyrics, but my friends break in to it often enough that it's worthwhile.)