fortune | say
The Mac will speak the fortune...
[robg adds: Yes, this is a very simple Unix hint ... but for those new to the Terminal, it might provide some learning value. The vertical bar (|) is the pipe symbol, and it takes the output of the first command (fortune) and sends it to the second (say). If you don't have fortune installed, you can obviously use most any other command; try ls | say in a small directory, for example.]

