I've gotten word of two downloadable versions of Mozilla--the pre-alpha version of Netscape Communicator 5.0--that are currently available. It's pretty likely that others are available as well; if you hear of any, please let me know.
The first is a 3.5 MB download that requires you to have a valid Netscape Communicator 4.0 install. You can get this one from an FTP site
Also available is a 128-bit version from Australia that doesn't require a prior 4.0 install. This version is now available from the Cryptozilla Web site.
Some notes on these builds: they are not very stable, though I had very little problem with either on Windows 95 (oddly, they were worse off, for me anyway, in Windows NT). Since this is an early build, the rendering engine and basic UI appears to be straight out of Navigator 4.0. Still, if you've got to have the very latest and want to put it through the paces, then this is it.