Parrot is a project mainly written in Ruby, it's free.
parrot bot for twitter
Parrot bot is a program that runs from the command line. It automatically follows people who follow its account. If you send a direct message to the parrot bot account, it will re-tweet them automatically.
Requirements:
Runs from the command line Automatically follows people who follow this account Automatically re-tweet direct messages Read Twitter account credentials from a configuration file
Usage: parrot [options] -p, --parrot Re-tweet direct messages -f, --follow Automatically follow users who are following me -v, --version Show version -h, --help Show this message