Texas Hold 'Em Probabilities to Know

When you hold:
A pocket pair-you will flop three of a kind or better 11.8% of the time.
AK-you will flop at least one A or K 32.4% of the time.
2 suited cards-you will flop a flush 0.8%, and a four flush 10.9% of the time. You will make a flush 6.5% of the time if you stay in until the end.
2 unmatched cards-flop a split two pair 2.02% of the time.
King high flush-will be beaten by ace flush less than 6% of the time, when a three flush on board and ten players are dealt cards.
Trips after flop-will wind up full house or better 33% of the time.

from Hold 'Em Poker by David Sklansky.