Craps is a casino game where you actually stand a pretty good chance against the casino. 

One of the best bets in Craps is the Odds Bet, since the casino don't have an edge on this bet. This means that it pays fairly according to the odds, which is not the case in many bets in casinos. The odds bet can be made on the pass, don't pass, come and don't come bets, once the point has been established. Craps tables usually have some sign or writing stating the maximum you can bet on odds - 1, 2 or 3 times the original bet is most common. In the long run, you can expect to get even with the casino on the odds bet. The downside is of course that you have to have a bet already to make the odds bet. Sometimes it is possible to buy another player's odds bet, if he cannot afford it or isn't betting it to the full. Nekojin says that is very rare

The best bet, which is the only possible way the have a theoretical edge over the casino, is to buy a Don't Come bet from another player. When you place a "don't come" bet, the next roll will be treated as the "Come Out" roll  - you lose on a 7 or an 11. After the first roll, you win on 7 and lose only on the point, which at its worst give you a 6 to 5 advantage. You play with the casino, against the other players. Now, if a player want to remove his Don't Come bet for some reason, try to buy it. It's the best bet there is. 

Here are the true odds for the different combinations of the dice in a craps game. 

Total      Combinations                  Number of  Odds 
Dice       possible                   Combinations  versus a 7
--------------------------------------------------------------------
2          (1,1)                                1   6 to 1 
3	  (1,2) (2,1)                          2   6 to 2 = 3 to 1 
4          (1,3) (3,1) (2,2)                    3   6 to 3 = 2 to 1 
5          (1,4) (4,1) (3,2) (2,3)              4   6 to 4 = 3 to 2 
6          (1,5) (5,1) (4,2) (2,4) (3,3)        5   6 to 5 
7          (1,6) (6,1) (2,5) (5,2) (3,4) (4,3)  6   1 to 1 
8          (2,6) (6,2) (3,5) (5,3) (4,4)        5   6 to 5 
9          (3,6) (6,3) (4,5) (5,4)              4   6 to 4 = 3 to 2 
10         (4,6) (6,4) (5,5)                    3   6 to 3 = 2 to 1 
11         (5,6) (6,5)                          2   6 to 2 = 3 to 1 
12         (6,6)                                1   6 to 1 

 

Finally, a nice drawing of the table for reference. 

	   Dealer stands         Boxman sits          Dealer stands
	       here                 here                  here
   #######################################################################
  # __  ____________________    $$$$$$$$$$$$$    ____________________  __ #
 # | d||DC| 4| 5| 6| 8| 9|10| +---------------+ | 4| 5| 6| 8| 9|10|DC||d | #
 # |Po||__|__|__|__|__|__|__| |any seven   4-1| |__|__|__|__|__|__|__||oP| #
 # |An| ____________________  +===============+  ____________________ |nA| #
 # |St||     C O M E        | |hard 4 | hard 6| |     C O M E        ||tS| #
 # |Sp||____________________| |-------+-------| |____________________||pS| #
 # |La| ____________________  |hard 10| hard 8|  ____________________ |aL| #
 # |Is||2  3 4  9  10 11  12| +===============+ |2  3 4  9  10 11  12||sI| #
 # |Ns||_______FIELD________| |two    |  three| |_______FIELD________||sN| #
 # |E |_____________________  |-----HORN------|  _____________________| E| #
 # |      don't pass bar 12 | |eleven | twelve| |    don't pass bar 12   | #
 #  \________PASS_LINE______| +===============+ |________PASS_LINE______/  #
 #                            |  any    craps |                            #
  #                           +---------------+                           #
   #                               /dice\                                #
    #####################################################################
                             Stickman stands here
                                   

(ASCII art from rec.gambling)