Where can I get a Linux ISO image?

Check out http://www.linuxiso.org for a grand collection of downloadable linux ISO images. It should have most distributions available.

Look at Debian's image site to get a downloadable ISO image of the best distribution in the world :-). Ofcourse the real diehards do net installs.

For masochists there's Linux from scratch (LFS), which does not come in binary downloads.