Rather than navigate with Links to the mirrors page, pick a mirror, download the stage and portage snapshot, why not download both of them in advance? Usually there is a working PC before a new Gentoo is built. I've done the last few installs this way and it saves a lot of time. Download the minimal ISO, burn it but do not finalize the CD. Reopen the CD and continue the session, and add stage3 + snapshot to the compilation, then finalize. Now when the time comes you can just tar from the CD without having to download.
Thanks for the suggestion, but no. :) If you want a CD + stage tarball + Portage snapshot, then grab a GLI liveCD or Universal liveCD (depending on your arch). Besides, if you're using an internet connection to grab things (i.e. doing a networked install), you'll want to download a more recent Portage snapshot anyway, rather than use what's on the CD you just created. PLus, it takes more time to download a tarball + snapshot and burn them to a minimal CD rather than just downloading and immediately untarring, anyway. ;)