There is already another app called frog jump similar to this.
But this sounds good. and is slightly different compared to that.
For power ups you can try
1) slow down mode : which slows the scrolling of the screen, so u can jump perfectly
2) automatic jumping mode : no need to tap , the frog jumps automatically for say 10 secs
3) fast forward mode : where screen scrolls faster and take u further up but without falling in the water.
4) invincibility mode : even if u tap wrongly u should not fall and instead jump correctly on the leaf
these are just my suggestions.. thanks for such a nice funny app.. will leave a good rating on gplay.