Prism is a small step in that direction. You can turn off the menubars and make a webpage look like an app. But Prism doesn't play well with UNIX: from the command line, you can start it and stop it, not much else.
Uzbl sounds like you'll be able to do neat things: (haven't looked at it, but here's my imagination:) log your clickstream to STDOUT, filter URLs clicked on with a shell script (ad-block implemented in perl regexes), re-implement greasemonkey with "perl -pe 's/foo/bar/g'", etc.
As an aside: I can't use the web without Mozilla's keywords: "g foo" does a google search for foo, "w foo" does a wikipedia search, "imdb foo" does an IMDB lookup, "to foo" uses google maps to tell me how far a way a city is, etc.)