here some nice apps for iphone/ipad :
http://avatron.com/apps/air-display/
http://eyosido.com/eyocontrol/surface/
http://hexler.net/
http://liine.net/en/products/lemur/
http://www.neyrinck.com/
http://saitarasoftware.com/Site/Home.html
http://www.spectrasonics.net/news/news-content.php?id=53
etc…
have fun ! 