man tar says that OS X's tar implementation should be able to extract .iso files. tar creates and manipulates streaming archive files. This implementation can extract from tar, pax, cpio, zip, ...
Every time I try to download or save a .tar.gz file, I get something like this: The popup is simply wrong, I've used the right .tar.gz extension. Clicking on Use .gz saves the file as .tar.gz, and ...