http://www.apple.com/airportexpress/
A great gadget to add to your wireless network if you use iTunes, if you've got a hi-fi you are no longer using and end up listening to you songs through the crappy speakers on your laptop, adding one of these to the wireless network (which does not have to be Apple, mine is attached to my Linksys WRT54G) allows you to stream from iTunes to the HiFi. Quality is not perceptably different from the original (128k MP4 - iTunes default).
And you can plug your printer into it (see post 6 above).
In fact it is a pretty good product to use as your wireless network base, the only disadvantage is that it only has one cabled point (for the Cable Modem) so you would need a hub to attach other wired peripherals through it.