There have been several posts asking for flop odds lately. This chart puts most of the important flop odds all together.

Texas Hold'em Flop Odds

Common odds when holding unpaired hole cards:

Code:
flopping EXACTLY one pair by pairing a hole card                                    26.939% 
flopping EXACTLY two pair by pairing a hole card AND pairing on the board            2.02%
flopping EXACTLY two pair by pairing EACH of your hole cards                         2.02% 
flopping EXACTLY trips by flopping two cards to one hole card                        1.347% 
flopping EXACTLY a full house, trips of one hole card and pairing the other          0.092%
flopping EXACTLY four of a kind, three cards to one of your hole cards               0.01%
Common odds when holding paired hole cards:

Code:
flopping EXACTLY two pair by pairing the board                                      16.163% 
flopping EXACTLY trips by flopping a set for your pocket pair                       10.775% 
flopping EXACTLY a full house, a set to your hole pair and pairing the board         0.735%
flopping EXACTLY a full house, by the board tripping up                              0.245%
flopping EXACTLY four of a kind, two cards to your hole pair                         0.245%
Common odds when holding two unsuited cards:

Code:
flopping a four flush                                                                2.245%
Common odds when holding two suited cards:

Code:
flopping a flush (including the slight chance of a straight flush in some cases)     0.842%
flopping a four flush                                                               10.944%
Common odds when holding connectors from 54 to JT

Code:
flopping a straight (including the slight chance of a straight flush in some cases)  1.306%
flopping an 8 out straight draw*                                                    10.449%
Common odds when holding one gapped connectors from 53 to QT

Code:
flopping a straight (including the slight chance of a straight flush in some cases)  0.980%
flopping an 8 out straight draw*                                                     8.08% **
Common odds when holding two gapped connectors from 52 to KT

Code:
flopping a straight (including the slight chance of a straight flush in some cases)  0.653%
flopping an 8 out straight draw*                                                     5.224% **
Common odds when holding three gapped connectors from A5 to AT

Code:
flopping a straight (including the slight chance of a straight flush in some cases)  0.327%
flopping an 8 out straight draw*                                                     2.612% ***
Notes

* An 8 out straight draw includes open ended straight draws and double barrelled gut shots.
** The odds are 0.327% less for the combinations on the edge as they have one less opportunity for a double barrelled gut shot.
*** Only the 95 and T6 three gappers have the posted 8 out draws, all the other three gappers have a lower chance. The closer the three gapper is to the edge, the lower the chance.