iSofa is a free software (or donationware) that lets you control your Mac from your iPhone / iPod Touch

iSofa is a free software that lets you control your Mac from your iPhone / iPod Touch:
• Keynote Remote
• iTunes Remote
• VLC Remote
• DVD Player Remote
• QuickTime Remote
• FrontRow Remote
• iTunes Alarm Clock Remote
• Browser / Launcher
• Screen wake up
• Screen sleep
• Screensaver launcher