BTT Remote
BTT Remote is a handy little iOS app which acts as a remote control for your Mac. It is very customizable through BetterTouchTool.
Note: If you have purchased BetterTouchTool you can use BTT Remote for free. (It also goes the other way around - if you purchase BTT Remote on iOS you get a free BetterTouchTool license)
https://itunes.apple.com/us/app/btt-remote-control/id561676304?mt=8