Both Ubuntu and Fedora install from a CD-sized ISO file which doubles as a live booting environment. In the modern world, that's less than 1% of the storage of even a "small" laptop. And it's only slightly larger than iOS5 or Android installation bundles.
How much "lighter" do you really want it to be?
If you really have storage requirements that won't fit a desktop distribution, try something like buildroot (http://buildroot.uclibc.org/) or Yocto (http://www.yoctoproject.org/), which are better targetted at that kind of environment.
Both Ubuntu and Fedora install from a CD-sized ISO file which doubles as a live booting environment. In the modern world, that's less than 1% of the storage of even a "small" laptop. And it's only slightly larger than iOS5 or Android installation bundles.
How much "lighter" do you really want it to be?
If you really have storage requirements that won't fit a desktop distribution, try something like buildroot (http://buildroot.uclibc.org/) or Yocto (http://www.yoctoproject.org/), which are better targetted at that kind of environment.