Cows are a big part of my computing life. They're also pretty funny. (Especially when they have firearms, or when they are used for covert military operations. But that's another matter.) There is a cow living on top of my monitor at work. ASCII cows have been wandering in herds around the net for a long time, bringing good will and unnecessary bovine humor to all who meet them.
Cows have been a big part of the history and culture of the Computer Science Undergraduate Association at the University of California at Berkeley. The cows traditionally seen there before I joined the organization were very limited in what they could say and do. I wrote cowsay in an effort to remove some of those limitations.
cowsay is basically a text filter. Send some text into it, and you get a cow saying your text. Very easy to use, I would hope. All you need is a working installation of Perl 5. And if you think a talking cow isn't enough, cows can think too. All you have to do is run cowthink.
If you're the type to try out beta software, then Cowsay 4 may be for you!