Debian can be installed from floppies (but you need 6). Fedora Core 1 can be installed from 1, but 2 doesn't have a floppy installer. I think Slack has a floppy install. Mandrake used to. FreeBSD and NetBSD can be (but they're not Linux). All of these options require a network connection, as the only thing that will fit on a floppy is a kernel and a few lightweight utilities. Even Windows 3.1 required 4 disks!
The last floppy OS was DOS 6, as far as I know.
If your concern is a lack of CD burning equipment or no broadband connection to get the stuff and no real cash to lay out for a real boxed set, you might wanna consider one of the many online services that will burn the distro of your choice for the cost of the disks and the mailing. I used to use The Computer Helper Guy
when I was on dialup.