If you've got this far then you probably have some ideas about what you want to do with your Raspberry Pi and you've probably keen to try to use some other USB devices with your Pi, but both USB ports are already being used (by the keyboard and mouse). The obvious answer is to use a USB hub to provide more ports.
You can use a powered hub if you wish, but as long as your Raspberry Pi power supply is up to the job and you don't connect too many peripherals, then you will be ok with a non powered hub like the one shown above, which is available from Cut Price Cables. Simply plug the hub into one of the USB ports on your Raspberry Pi and this will give you four USB ports which can be used for keyboard, mouse, and other peripherals.
Although not essential, I would strongly recommend that you invest in a case for your raspberry pi. This will keep your Pi in pristine condition and prevent accidental damage of the PCB. The case shown above is available from Cut Price Cables in a range of colours, but personally I think it looks best in black.