I know that lots of other people also find that their @computer context can get quite big and unwieldy. Here are my distinctions or sub-contexts for this, to help break up the list:

@online (self explanatory)
@offline " "
@web research (all the googling/browser based searching around tasks)
@encrypted login (I use a separate login for all financial stuff, so this context means that I can do all those tasks when I switch logins)

I'd love to hear how others break @computer up into smaller contexts.