Building on Ken's answer: I used fuse4x and fuse-ext2 successfully, and I recommend fuse-ext2 over ext4fuse.
ext4fuse was a hassle for me, because it requires manual compilation and has no support for fuse4x options that would allow me to set access control. fuse-ext2 provides downloadable packages, and the 0.0.7 version worked just fine. I copied a few large ISOs over without any problem.
