In addition, Firefox 3.5 boasts support for location-aware browsing, a new feature that may strike some users as incredibly cool, and others as creepily Orwellian. Sites that employ location-aware browsing can use data about the network to which you're connected to plot your geographic position--for example, to automatically bring up a list of all the restaurants within three blocks of your computer.

Privacy buffs will be glad to know that this feature's strictly opt-in. Firefox 3.5 clearly warns you when a site wants to learn your location, and it lets you grant sites access on a case-by-case basis. Besides, for now the feature seems to exist only on a handful of test pages, in which it's used only to display your current location on a map.

Firefox 3.5 does more than any previous version of the browser to keep your surfing safe from prying eyes. Mozilla has finally implemented its own version of Safari's "Private Browsing" feature, which works as advertised; once in private mode, you can surf to all the sites you like, and leave no trace behind in your history. I also noticed one particularly big improvement in Firefox's ability to automatically erase your private data when you quit the program: It no longer pops up an aggravating dialogue box to get your permission every time. Instead, you can set which parts of the browser you want wiped within the Preferences menu, and never worry about it again.

Another savvy addition proves better in theory than in practice. While browsing your history, you can right-click any site and select "Forget This Site," to remove all traces of it from your browser--with one catch. Firefox deletes pages from a site based on the exact domain name. So if you initially surf to "google.com," and subsequent links from that page take you to "www.google.com," selecting "Forget About This Site" on one of the "www.google.com" pages won't remove the "google.com" one. Mike Beltzner, director of Firefox development, said the programmers were "erring on the side of caution," since different subdomains could represent entirely different sites. However, he said refinements to this feature are under consideration for future releases.