Show PATH in a human-readable way

You can use tr.

$ tr ':' '\n' <<< "$PATH"
/Users/arturo/.rvm/gems/ruby-1.9.3-p392/bin
/Users/arturo/.rvm/gems/ruby-1.9.3-p392@global/bin
/Users/arturo/.rvm/rubies/ruby-1.9.3-p392/bin
...

You can also do this in some shells (tested in bash and zsh):

echo -e ${PATH//:/\\n}

In zsh, you can use the $path variable to see your path with spaces instead of colons.

$ echo $path
/Users/arturo/.rvm/gems/ruby-1.9.3-p392/bin /Users/arturo/.rvm/gems/ruby-1.9.3-p392@global/bin /Users/arturo/.rvm/rubies/ruby-1.9.3-p392/bin /Users/arturo/.rvm/bin

Which can be combined with printf or print.

$ printf "%s\n" $path
/Users/arturo/.rvm/gems/ruby-1.9.3-p392/bin
/Users/arturo/.rvm/gems/ruby-1.9.3-p392@global/bin
/Users/arturo/.rvm/rubies/ruby-1.9.3-p392/bin
...
$ print -l $path
/Users/arturo/.rvm/gems/ruby-1.9.3-p392/bin
/Users/arturo/.rvm/gems/ruby-1.9.3-p392@global/bin
/Users/arturo/.rvm/rubies/ruby-1.9.3-p392/bin
...

The <<< operators are called herestrings. Herestrings pass the word to their right to the standard input of the command on their left.

$ cat <<< 'Hello there'
Hello there

If your shell doesn't support them, use echo and a pipe.

$ echo 'Hello there' | cat
Hello there

Here's a quick way with bash

OLDIFS=$IFS IFS=: arr=($PATH) IFS=$OLDIFS
printf "%s\n" "${arr[@]}"

Expanding on Smith John's solution, this makes for a nice alias in your .bash_profile:

alias MyPath='echo -e ${PATH//:/\\n}'