Portable Offline Internet Browser

Sounds strange doesn't it, hehe. Being a student who doesn't have internet at home, it would be extremely useful if there was a portable web browser (or plugin; to Firefox of course) that was able to save websites in a cache on your USB so you could browse the sites later.

I had this in mind because I have discussion boards for some of my online classes, but I often don't have time to read them until later at night when the school is closed.

Some suggested features:
** Downloaded sites have the exact same look 
   and functionality.
** Sites would only be saved from a command 
   in the context menu or on toolbar. This 
   could prompt you for how many links deep 
   to save, any filters you'd like to apply, 
   and the option to run in the background so 
   you can still browse while it's saving.
** Also, links that are not saved in the cache 
   could be displayed with a different color 
   or show a different cursor.

I'm pretty sure there are many who could use a program like this. I hope to see one in the near future. I've tried Breadcrumbs but it lacks some features that would make it a lot more user friendly. It doesn't seem to recognize when the browser is offline and it doesn't have a list of currently available offline sites that have been saved. Also tried SpiderZilla but it's buggy and causes problems with some firewalls or something. Thanks.