It does sound silly to the rest of the world - mozilla for 030s, but mozilla running on a Mac Quadra 40Mhz/68040 was nowhere near as bad as I expected. It took a good while to load, but once it'd finished that thrashing about it was pretty usable. Not something I'd like to rely on browsing for several hours at a time with, but it made me want to just pat the little 040 for putting in the effort =).
The big problem was the UI, which seemed to take up half of the 640x480 res the machine was running in at the time!. Considering that's supposed to be one of its slower points, I imagine dropping that for a native UI would make things just a little better.