perhaps you didn't know that your iPhone or ipad touch can act as a wi-fi remote for many hardware devices and software applications. you simply connect the iPhone throw Wi-Fi to the same local network,through in many cases you will also have to install a pc utility that listens for instructions from your iphone over the wi-fi network.here are many fevourate tools for controlling PCs and other devices
I-CLICKR POWERPOINT REMOTE(www.senstic.com)
it manages presentations,even displaying your speaking notes or upcomming slides on the iphone.its a great counterpoint to the remote available for APPLES MAC-ONLY keynote tool in iwork.
switching to the topic of pc controllers,AIR MOUSE PRO (www.mobileairmouse.com) acts as a computer keyboard and mouse,so you can command your system from across the room.AIR MOUSE PRO'S clean design and application-specific functions make this utility standout among a crowd of APP STORE compititors.for a free app that does pretty much the same thing,give REMOTEPAD FOR IPHONE(www.temjin.org/remotepad) a shot.
the APP store also sells many VNC(virtual network computing)clients,which let your iphone see and control the pc screen.look to those if you already have VNC server software runnig on your pc,otherwise i like the $30 LOGMEIN IGNITION for its easy setup and interface with LOGMEIN remote access software
staying on the PC, if you use the highly popular VLC player to play your media files, then you can use VLC Remore(www.hobbyistsoftware.com /VLC-more.php) to control playback with your iPhone. the free version allows basic playback and vloume controls where as if you purchase the full version for $0.99, you can even loads files on the player.