Editing suite for videos and photos.
Social networking (I don't use them,but if you want to bring people from Win/Mac you better have Inyourfacebook/Twit/Whatever
Office suite
Web suite like Seamonkey(surf,mail,web publish,etc.)
That pretty much covers non-game computer for average person.
For others more advanced : software writing tool suite, process/remote control software(run house/automate telescope or ?, top quality CAD/CAM ,modeling programs .
