Useless coins!

[hwille]

I have completed all 120 current levels and have amassed 994,820 coins - coins that are absolutely useless! I've never found a way to use a single one. I would love an explanation.

[fleischt]

I agree about the coins (just finished level 138 and have tons of these I've never used).
I don't use the boosts but would consider it if you could use the coins for better ones....or what about buying some extra lives with them?
I would do that when I'm bored and out of lives and want to keep playing.