PaulTheOctopus is a project mainly written in Ruby, it's free.
Paul the Octopus is a Twitter bot that predicts from the given options
@octopuspaul42 predicts the future or answers any question. It is the Twitter version of Paul The Octopus. It predicts using a complex algorithm involving Number 42.
Just Follow and reply to @octopuspaul42 with your options in boxes [...]
Example:
John: Hey @octopuspaul42. When will i win the lottery? [Today] [Friday the 13th] [Birthday] octopuspaul42: @John: Birthday