Common Mahjong wait patterns
I found a basic answer on my question over here:


  Try to go out waiting for multiple
  tiles (not just one). Imagine that you
  have three complete sets and two
  pairs. Imagine that one pair is 2
  Bams, and you draw a 3 Bam from the
  wall -- which tile do you discard now?
  In this situation, many experienced
  players will discard a 2 Bam, keeping
  2-3. A two-way incomplete chow call is
  better than a two-pair call.
  
  Learn to
  shape the hand into calling patterns
  that give you multiple chances to win,
  such as the following:

Tiles in hand     Call for 

2223              134 
2224              34 
2223344           2345 
2223334           2345 
2223456           14736 
22234 RR          25 R 
23456             147** 
34567             258** 
45678             369**

  
  Highly skilled players of
  un-American mah-jongg (since American
  style alone does not use "chows") know
  these patterns by heart. More complex
  call shapes are mostly extensions of
  these. Although the American game does
  not use chows, the strategy of having
  a multiple-tile call still applies to
  that game as well.
  
  Of special interest
  is the complexity of the pure hand. If
  you're working on a pure hand, it can
  often be difficult to tell what all
  the tiles are that can complete the
  hand. For instance:
  1-2-3-4-5-5-5-6-6-6-7-8-9 (5 chances);
  1-2-3-4-5-5-5-5-6-6--7-8-9 (5
  chances); 2-3-4-4-4-5-5-5-6-6-6-7-8 (7
  chances); and of course
  1-1-1-2-3-4-5-6-7-8-9-9-9 (9 chances).


Edit: Additional links with a lot more waits


http://saki.wikia.com/wiki/Mahjong_waits
http://saki.wikia.com/wiki/Complex_waits
http://www.reachmahjong.com/en/forum/viewtopic.php?f=5&amp;t=52599


Especially the latter is, from my beginner eyes, insanely exhaustive.