Speaking as a Ruby user, I think nil and the entire behaviour around truthyness and falseness are wrong. I should be able to create my own nil objects, and I especially would love to be able to create false objects that carry more information.

For example (and there are code smells in this, but it gets the idea across):

    if account = Account.create(params[:account])
      ...
    else
      complainAbout account.errors
    end

Truthiness should not be reserved for whether an object exists, it could also be used for whether it is valid, complete, or anything else.

My particular example might not be a great one, but I think framework and library developers ought to be able to work a consistent use for truthiness and falseness into their creations, e.g. a true object has been saved, a true object is valid, a true object is complete, a true object represents the current state of the world instead of the past or future or a wrong state, and so forth.