VirtualDJ Remote is an application for iPad/iPhone/Android/iPod touch/etc, that let you use your devices as an additional interface for VirtualDJ.
The remote is completely skinnable, and use the same skin format as VirtualDJ. You can download remote skins from this website, or easily create one yourself.
The versatility of the skins means your remote can be anything, from a turntable-like scratch pad on your tablet, a drum-pad to launch samples, a basic play/pause/loop controller, or a playlist monitor to let you work from the bar.
The remote connects to VirtualDJ wirelessly, and the connection is completely secure.