Here's what seems to be an archive of the latest version of GMCL:
http://goggole.dip.jp/infoseek/20101...0/default.html. I haven't checked every page for completeness, but it does seem to have the composer and game lists intact.
There are a few GMCL revival projects on @wiki:
http://www16.atwiki.jp/gmclw/ and
http://www36.atwiki.jp/gmcomposer/. That first one in particular has had quite a few updates, but I can't attest to its accuracy. (Akihiko Mori is the Don behind Galaxy Robo? Really?)
As for JGML, I can't remember when the last time I used it was. Definitely a very important site historically, but I think it had mostly served its usefulness. A couple of VGM sites on Infoseek that I did still find useful from time to time were
Nirareba's vocal works lists and
BSM. Sad to see those go.
I've found a couple of Infoseek archive projects:
http://goggole.dip.jp/infoseek/LIST.html and
http://www.infoseek-archive.com/list.html. They don't actually have any of these sites, though, and I'm not sure they ever will.