Browsing has become much of a "add-on" these days, looking-up some info being a side-activity to what you do.
New browsers (such as DeskBrowse) appear that quickly pop-up and disappear after use.
However, there is something to be said for keepng your main browser, as it holds all your URLs, history, log-ins, etc. So instead of changing browsers, try using this AppleScript with Safari. It gently slides your main Safari window in and out at the left of your screen with a pseudo-Quartz effect (yes, AppleScript is fast these days) as you hold your cursor there for a second.
It can be best invoked by defining a left-edge mouse trigger in Quicksilver, but you may define a similar event in QuicKeys X3, etc.
[robg adds: I tested this one (using Butler and a screen hot corner), and it works as described.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20051222000951989