The 7th Guest is missing most of its tracks. The Fat Man has released both this soundtrack and the 11th Hour's soundtrack together on Bandcamp (here) but unfortunately the tracks are not labelled or even ordered by which game they're from and I'm not familiar enough with the series to help much. There's also this release of just the 7th Guest soundtrack that came with the game but it's missing some tracks I've heard in gameplay videos.
I think the first 3 7th Guest ReMixes are all labelled right, Microscopism is missing some sources. Mazedude's site lists the other sources as 'Microscope Puzzle', 'Cake Music' and 'Coffin Dance'.
I think 'Microscope Puzzle' is actually track 25, 'Bolero', as this video shows it playing during that puzzle. Bolero is the main source used in the ReMix.
'Cake Music' may be track 15, XMusic Box (the X might be a typo?), as this video shows it playing during a cake puzzle. It appears at 2:27 - 2:38 of the ReMix.
Coffin Dance is named on the soundtrack, and appears at 2:38 - 3:19 of the ReMix.
Mazedude's site mentions that there are more sources used but doesn't name them. I haven't been able to identify them.
Torvus Clockwork is missing Submerged Temple[Metroid Prime 2] (used throughout) and Main Theme[Metroid Prime 2] (0:18 of source used at 2:06 - 2:54).
In Your Prime also uses that same bit of Metroid Prime 2's theme at 1:44 - 2:34.
I've also found a bunch of brief cameos:
Cliffside Clamber - 2:14 - 2:33 of ReMix uses 1:17 - 1:31 of Northern Hempispheres [DKC] and 0:18 - 0:32 of Voices of the Temple [DKC] layered together.
Banaqua - 2:52 - 2:59 uses Title Theme [Donkey Kong]. I think 2:40 - 2:46 might also be based on 0:04 - 0:08 of Title [Donkey Kong Land].
All I Wanna Do - Possibly not intentional but the bass at 4:05 - 4:10 sounds a lot like the start of Vampire Killer.
Anthem of a Misguided Youth - 1:08 - 1:14 uses Flute [The Legend of Zelda] (or the Ocarina title screen)
KRool Intentions - 4:21 - 4:29 uses 0:24 - 0:28 of Boss Bossanova (Boss Tune) [DKC2]
Big-Band Battlefield - 4:44 - 4:47 uses Overworld BGM [Super Mario Bros.]
Life of a Bowling Pin - 1:42 uses Treasure Chest Catch Fanfare [The Legend of Zelda]
Rime of the Wanderin' Seafarer - 0:06 uses Secret [The Legend of Zelda]
Soap Globe - 3:02 - 3:08 uses Overworld BGM [Super Mario World]
Sword of Sand - 2:57 - 3:03 uses Above Ground [The Legend of Zelda]
Tutti I Frutti - The Ballad of Piantee Joe - 3:43 - 3:46 uses Invincible BGM [Super Mario Bros.]
The Submap Emissary - Another possibly unintentional one, but the end of the guitar solo (3:24 onwards) could be referencing 1:00 - 1:11 of Stickerbush Symphony (Bramble Blast) [DKC2]
La Montaña de los Caballos Jóvenes - 3:34 - 3:39 is the Chocobo Theme [Final Fantasy II] (or Techno de Chocobo for game consistency). I think there's another tune right after it but I don't know enough about FF to place it.
That's Not Funny - 1:55 - 2:05 of ReMix uses 0:26 - 0:35 of Ruins. 2:05 - 2:12 of the ReMix uses 0:09 - 0:12 of Heartache. 2:12 - 2:14 of ReMix uses 0:07 - 0:11 of Your Best Friend. 3:02 - 3:07 of ReMix uses 1:49 - 1:53 of ASGORE.
Drowning Blue - 2:18 - 2:26 uses the start of Pokémon Center [Pokémon Red Version]