GhostZilla is a web browser based on (if you can't tell by the name) Mozilla. GhostZilla is different, though, in that it is designed to be an extremely secretive web browser. GhostZilla is actually so good at what it does, it will probably redefine your view of "secretive."
Before talking about why GhostZilla is so secretive, let's first talk about it as a web browser. GhostZilla is actually quite dated, originally created as shareware in 2002, then gone freeware (woohoo!), then open source (woo-hoohoo!), then shut down (aww...). It does, however, have many features that are still around as must-haves; tabbed browsing, for example. Even though the tab bar is extremely small, there is indeed tabbed browsing support in GhostZilla, as well as bookmarks, history, password memory, form memory, customizable homepage, and proxy configuration (essentially everything that was in Mozilla 1.0.1). So if asked the question "Is GhostZilla a full-fledged web browser?", I would say "Yes".
I would like to quickly say that though GhostZilla is a "full-fledged" browser, it does take some getting used to. First, the menu bar ("File", "Edit", "Options", etc) is extremely skinny so that it does not draw the eye's attention. Likewise, the tab bar is MUCH thinner than any browser I've seen, and does not show a site's favicon by the title. Just thought I'd throw that in there.
Now for the secretive side. Rather than having it's own window, GhostZilla actually fits inside other windows, almost in a "parasitic" manner. The whole logic behind that is that if you open a window of a program that is easily recognizable, (like say, Mozilla Thunderbird), you can open GhostZilla inside the that program, giving the impression that you are not surfing the web, but doing something else (like checking your mail). Of course, GhostZilla is also secretive because it hides itself completely, even from the taskbar. When you want to use it again, touch the left side of the screen, then the right side, then the left again (a left-right-left motion). This will bring GhostZilla up inside whatever window is active. To hide GhostZilla, just move your mouse outside of GhostZilla's window, and it will become hidden again.
So that's how GhostZilla hides. But what about when you're using it? How is it really that secretive? Levels. There are 6 "Hiding Levels" that can be chosen from in GhostZilla. Here they are (almost directly copied from the GhostZilla manual):
Level 1: Looks regular, like a normal web browser.
Level 2: Web pages are shown in black and white. Big pictures are hidden, except for on mouseover.
Level 3: Same as Level 2, except big pictures are black and white.
Level 4: Same as Level 2, except pages are gray and white.
Level 5: Same as Level 4, except big pictures are black and white.
Level 6: Page is gray, pictures are gray and pale (and only shown on mouseover).
As you can see, each greater level adds something more to make the page less noticeable to the eye. The biggest eye catcher is -of course- pictures, which GhostZilla takes care of by auto-hiding them. If you use Level 6, the page is so gray, one could scarcely believe that you are checking Facebook, rather than doing your taxes (or some other boring activity). Or if you want to just use a browser that hides uber quick, use Level 1.
GhostZilla even handles ads. Pop-ups are not even allowed to exist, and on-page ads are handled by the "big picture" rules with the Levels.
So right about now, you're probably interested in this spy-browser. But then you think, "What about after GhostZilla is gone? What about footprints that lead back to me?" I mentioned history, bookmarks, etc, but does that mean that those are all left on the disk when you leave? Well, as for things like the cache (temporary internet files), they are "[stored] in Windows temporary directory", and GhostZilla "removes them all on exit". So it's kinda up to you; do you trust having files on the host computer, even temporarily? If so, then don't worry. If not, then perhaps a more paranoid browser is more your style.
But what about the "profile"? Bookmarks, history, and all that jazz? Well, GhostZilla lets you store all of that info in an encrypted archive. Because it is protected and not GhostZilla specific, no one looking at it will be able to tell that it's for GhostZilla. Of course, when GhostZilla came out, GhostZilla was meant to be run on a CD, and it was amazing that "you can choose to store the archive on a floppy!" Nowadays, you can have both GhostZilla and the profile on a USB drive. But anyway, it IS possible to save your bookmarks, preferences, and all that profile stuff, and it IS possible to use it next time. When you first start GhostZilla, it will ask if you want to load a profile, in which case you can if you have one.
Now let me take a brief moment, Freewarenites, to give a few precations. (A) GhostZilla is not untrackable. Schools and businesses and such log every web site access that is made, no matter the browser. This means that if you're planning on visiting inappropriate websites (whatever "inappropriate" means for your circumstances) and want to use GhostZilla to get away with it, you're going to be sorely disappointed when you get detention/fired/thrown in jail. And the most important part is DON'T COME CRYING TO ME IF YOU USE GHOSTZILLA AND GET YOURSELF IN TROUBLE. Fair warning. (B) GhostZilla may not be "legal". GhostZilla is no longer actively supported, and its home website is down and out. I do know that GhostZilla came under scrutiny from Mozilla (because it was trying to sell GhostZilla for $20...when it was based on open-source software...made by Mozilla). However, it came back online after it removed some of the proprietary stuff. However, it then again went offline in 2007, and has not been seen since. I don't know why it's gone. It might be a legality issue (though I doubt it). But just know that if Mozilla is still upset about GhostZilla being distributed, well, then I'm screwed. But you might wanna watch your back too.
GhostZilla is really a "full-fledged" web browser. It weighs about 26MB (which is a little lighter compared to Firefox or Chrome), and uses a good ~50MB of RAM, maybe more, depending on what you're doing. The best part of GhostZilla is that it is portable, because it makes it ten times more useful to be discreet on a computer that does not have GhostZilla installed. It's one of the most interesting web browsers you'll ever come across, and -even though I've never personally tried Mozilla (*gasp*)- I do love the feeling of having a Mozilla Coporation product under my fingers.
(As I mentioned, GhostZilla's homesite is gone. However, A+ Freeware is freakin' amazing enough to not only allow me to discover GhostZilla, but also to host the last known version, v1.0.1)
Visit GhostZilla (host site A+ Freeware) website for download