Agree with the numbers already posted for rainbow and monotone.

I calculated two tone slightly differently from everyone else. The way I thought about it is there are two ways to make a two tone flop: When the second card matches the first card and when the second card does not match the first card.

When the second card matches the first card then we want the third card to be one of the other three suits, so I set the equation up like this:

52/52 * 12/51 * 39/50 = 18.4%

When the second card does not match the first card then the third card has to match either the first card or the second card. There are 12 left of the first suit and 12 left of the second suit so the equation looks like this:

52/52 * 39/51 * 24/50 = 36.7%

These are the two ways to make a two tone flop, so add the probabilities together and you get

Probability Two tone flop = 18.4 + 36.7 = 55.1%