Many of the baby books and other resources have lists of ways to calm your crying baby.  Things like:

1. Try feeding her
2. Change her diaper
3. Hold or rock her
4. Walk around with her
5. She's too cold or too warm
6. Something is causing her pain--find it
7. Burp her
8. Overstimulation -- go somewhere quiet
9. Boredom -- she wants something different
10. Play some white noise, water running, etc.

A useful list.  But what they don't tell you is that the list repeats!  You could work your way to the bottom of the list, and she's still crying 20 minutes later.  Great!  Now start from the top again. 

So the list should end as:

11. Goto 1.