Never thought about that before but a few minutes thought landed me on the name "24x7". A web browser is a non-stop source of information, entertainment, knowledge etc.... in short just about everything. It never sleeps. It always works hard and tirelessly to provide us with all the latest and updated information. So i would name my browser as "24x7", just to denote the fact that it works for 24x7 to provide us with everything we need.