1. Office – Google Docs,Zoho

2. Feed Reader – Google reader,newsgator online etc.

3. Multimedia – online streaming sites like YouTube, Imeem,last.fm

4. Converters – Online video/audio/document converters are there .

and i can quote several other categories like Image editing,Games and everything else , with the increaing coordination between Web browsers and developers , it seems that one day all our local desktop apps would go on-line . technologies like google gears,adobe air are all making  these web apps look and perform faster so as to beat up their desktop counterparts , and the greatest advantage you get is Platform independence,anywhere access,no processing overload on your system ( except processing that javascript) .

Still many applications would remain on desktops, but any application that’s small can be shifted to online status, especially those nifty library management,hospital management etc.