Because of their small or non-existent footprint, micro-Linuxes are especially suited to run on laptops -- particularly if you use a company-provided laptop running Windows9x/NT. Or for installation purposes using another non Linux machine. There are several micro Linux distributions out there that boot from one or two floppies and run off a ramdisk.
See
http://www.linuxhq.com or
http://www.txdirect.net/users/mdfranz/tinux.html for details. You may find a FAQ and a mailing list about boot-floppies at
http://os.inf.tu-dresden.de/~sr1/boot-floppies/faq.html . Also a BootDisk-HOWTO is available. Thanks to Matthew D. Franz maintainer of Trinux for this tips and collecting most of the following URLs. See also the content of Console/Mini Distributions at
FreshMeat.
MuLinux by Michele Andreoli
tomsrtbt
http://www.toms.net/~toehser/rb/ "The most Linux on one floppy. (distribution or panic disk)." by Tom Oehser
BABEL
http://celsius-software.hypermart.net/babel/ "A mini-distribution to run games"
Xdenu
http://xdenu.tcm.hut.fi/ , quotating Alan Cox: "Xdenu is a small distribution program that installs as a set of DOS zips onto a DOS partition and gives you a complete X11 client workstation."
SmallLinux by Steven Gibson
http://smalllinux.netpedia.net/ Three disk micro-distribution of Linux and utilities. Based on kernel 1.2.11. Root disk is ext2 format and has fdisk and mkfs.ext2 so that a harddisk install can be done. Useful to boot up on old machines with less than 4MB of RAM.
cLIeNUX by Rick Hohensee client-use-oriented Linux distribution
ftp://ftp.blueznet.com /pub/colorg
You may also consider some of the boot floppies provided by various distributions falling into this category, e.g. the boot/rescue floppy of Debian/GNU Linux.
If you like to build your own flavour of a boot floppy you may do so manually, as described in the BootDisk-HOWTO or using some helper tools, for instance mkrboot (provided at least as a Debian/GNU Linux package) or pcinitrd, which is part of the PCMCIA-CS package by David Hinds.
Also you might try to build your Linux system on a ZIP drive. This is described in the ZIP-Install-mini-HOWTO.