See Programmer's Baseball Cards:
Press S to make the batter spit and keep pressing till the cards appear

Extra Teams (Microsoft, Robots & Wizbang):
First click the "Help" option then "About". Now right click twice when Wizbang appears on the first line of the copyright statement

Unlimited Strikeouts:
When you are up to bat hold CTRL+R and you will hear a gunshot sound, that means you have unlimited strikeouts, but if your player pops a fly groundout etc., you will lose the person you were batting with, just without a out. If you don't want it anymore, hold CTRL+R and you should hear a wipe away sound.

Go to Training:
Press CTRL + T