Home Protector can play sounds all day long....normal household sounds that will make anyone think that you are home. You can also record your own voice, of you yelling at the kids :-) and import that into 'Home Protector' and play that at any time you wish. Anyone standing outside your house deciding whether they will break in or not, should then hear your voice. They should also hear you vacuuming/washing the dishes/washing clothes and cooking dinner....and even flushing the toilet!
The OS X application comes with a wide category of pre-recorded sounds, including categories like Bathroom, Cleaning, Kitchen, Office, and even sounds according to gender (e.g. male cough, female snoring). Even better, you can record your own sound clips to customize and really make it sound like you're the one home (oh, the fun random things one could record). But note, you'll need a decent set of speakers for Home Protector to fool anyone, so if you're a MacBook/MacBook Pro user, those built-in speakers aren't going to cut it.
The Home Protector application is available for $4.99 at the Mac App Store.