List of Killer Applications
This list is based on killer categories and then lists the application that has market share and/or is a superior product in the category. Web sites are not listed here even though many sites have app-like services e.g. ESPN with live sports scoreboard or Amazon wishlists or portfolio apps. Everything listed here is just my opinion and best guess.
Killer apps are mainstream or apps that are stellar and primed to go mainstream.
Web Browser: Internet Explorer 6 – 7; Firefox 2
Email: Outlook, Apple Mail, Thunderbird 2
Calendar: Outlook, iCal
Instant Messenger: Yahoo!Messenger, iChat
Music/Video: Windows Media Player, iTunes
Photo: iPhoto, Picasa
Web Applications (mainly US) –