This is an idea KeronianKnight had earlier for the daycare centre:
You can pay money to train your mcMMO.
Now, I know that many players have an extremely high amount of money, so, the proce would be high. A possible example;
There is a selection of signs with the different mcMMO stats. You right click a sign and a message will appear saying you have 'put that stat? in the daycare' Possibly, each step you take will add 1 exp point towards the overall level. Each exp point could cost, say $100 in game money, and then each time a stat levels up, it could cost another set amount $1000 maybe? even $10k?
Not exactly sure how this would work, or even if its a good idea. Just a suggestion.
Also not sure if this belongs in plugins or suggestions..