Hi

How about a nonsens-skilltree?

one skill could be te ability to dance.

So wasting 1 point to this skill makes your character beeing able to dance while standing.

Wasting 2 points gives the character the ability to dance while walking.

3 point: dance while runnning

4points: dance while fighting.

At the end the charakter can dance all the time. In an _action_rpg! :D

Maybe one can make a second bonussystem where one gains points  that are meant to be spent in the nonsense-skilltree.

An other skill could be the ability to fart. So the more points you waste, the more and harder the character farts.