If you're short on desktop space, and need a wireless router, there aren't a lot of things you can do. You could put it on your desk, at the expense of having power cords and ethernet cables hanging all over the place.
If this doesn't sound tolerable to you, Gigabyte has the perfect solution: The AirCruiser GN-BC01 is a WiFi 802.11g router that comes in the form of a PCI card. It connects to any PCI slot, though it only uses it to draw power. This allows you to turn any desktop into a fully functional WiFi G router, that will even work when the system is powered off.