Yeah, I now use it on a flash drive for school, or when I have to use other peoples computers. You can even set it up pretty much invisibly on a friends computer so it will always be there when you need it. It's speed come mainly from the mozilla rendering engine without the added bloat of the front end of Firefox.
Whenever I'm running Windows Vista (very rare now), I often use K-Meleon for it's speed. The fact that it uses the same rendering engine as Mozilla Firefox, and still runs faster convinced me into using it. It was definitely a great browser, however, on Vista (and XP), Opera seemed to run a bit faster. I don't have any numbers, but just from loading pages and downloading files, Opera feeled a bit faster. Even then Opera, although being my favorite browser, is unable to render some pages the way they were programmed. Since the rendering engine on K-Meleon is the same as Firefox, pages appear just fine and with a decent speed. So, in conclusion, in Vista I'll normally using K-Meleon as a replacement for Firefox, though on XP I stick with Firefox since it doesn't slow down my computer as much as Vista.
After trying lots of web browsers, I stop trying and continue to use Firefox as my main web browser. Now I'm waiting for Firefox3.
It's my backup browser when I'm forced to use a win32 OS (after SeaMonkey, which is my main browser).
Both are so faster and lighter than Fx....
I almost never use it. I'll occasionaly use it to test if a site is well rendered on different browsers. But that's all.
Firefox is the first choice and other browsers are also preferable, like Opera, Maxthon, IE7 or Safari. One more for the road? No.