There are six ways a batter can get to first base without hitting the ball. What are they?

I can think of four in softball. Four balls, if the pitcher balks, if they are hit by the ball, and if on the third strike the catcher drops the ball they can run to first.

A walk, hit by pitch, dropped third strike, and catcher's interference makes four.

According to Official Rule 7.05 (h), the batter and base runners get one base "if a ball, pitched to the batter or thrown by the pitcher from his position on the pitcher's plate to a base to catch a runner, goes into a stand, or player's bench, or over or through a field fence or backstop, or is touched by a spectator."

Alternately, according to 7.05 (i), "on ball four or strike three, when the pitch misses the catcher and lodges in the umpire's mask or paraphernalia," the batter and runners are entitled to advance one base. That is, if they can stop laughing long enough.

http://www.mlb.com/mlb/downloads/y2007/07_the_runner.pdf