Is it possible to configure bash to autocomplete with one tab like zsh?

Put this in your ~/.inputrc:

set show-all-if-ambiguous on

For additional credit, add:

set completion-ignore-case on

All of the options are in the GNU manual...

I do not have enough reputation to comment, but I would add to jasonwryans answers that it can be added to .bash_profile or .bashrc by writing them as:

bind 'set show-all-if-ambiguous on'
bind 'set completion-ignore-case on'

I case anybody else finds this question as I did.