RemoteBuddy works very well. I use it to control one older G4 Mac mini which is functioning as a media center in the study. Has a remote function, a remote keyboard and even a remote screen function as well as a ton of other features.
And Snatch has 10(?) customizable buttons that can be assigned to keyboard shortcuts. Also, multi-touch is used as TheZimm posted but also two fingers scrolls a page up and down. There is also a keyboard that works instantaneously, as with the trackpad function. Snatch is definitely the best on the App Store, but it is only for Mac. If you primarily use a Mac, GET IT!!!