Xmas Bonus Show! Direct Download: 
You don’t have to listen to this show, I promise! Noah actually says not to listen to it, and tried his best to prevent this show from happening.
1. “Jingle Bells,” Track 9 on the Tenchi Muyo! Ryo Oh Ki Christmas Album. Not available in North America (imports only).
2. “Joy to the World” although I don’t know the Japanese name or track number, it’s on the Tomoeda Shougakkou Chorus Club, a Card Captor Sakura Christmas album, not really available in North America. Try looking for it here.
3. I don’t know what this track is called or which album it’s from, but maybe you can figure it out by read this page. It’s definitely from a Live Action Sailor Moon soundtrack.
4. “Christmas in the Silent Forest” by by Ilaria Graziano, track 10 on the Ghost in the Shell Stand Alone Complex OST 3. Apparently it was the fourth opening theme of SAC in the first season, but Cartoon Network doesn’t want you to know that!
5. A Podsafe Christmas Song by Jonathan Coulton. You can download it from that link and use it on your own show and stuff. You can even give him a tip!
6. “We Wish You a Merry Christmas” also from Tomoeda Shougakkou Chorus Club, the CCS Christmas album.
Yeah… I like truly terrible things like Japanese Christmas Music
So…
Its become a bizarre self-inflicted tradition that while I can’t stand any Christmas music before Black Friday or even Dec. 6th (St. Nicholas Day) and only sparingly until the 20th, I end up listening through my collection after Xmas and this episode got sorted into the playlist.
2. is translated to ‘Morobito Kozorite’ and its Track 5 on this Image Album highlighting Iwao Junko (Tomoyo’s Seiyuu).
3. is Koibito ga Santa Claus and I think the version you have is sung by Fukami Rika (Sailor Venus) on a Xmas idol cd for the Anime. Here’s the Lyrics: http://www.animelyrics.com/anime/smoon/smsanta.htm
6. ‘Omedetou Christmas’ Is also Fukami Reika (Sailor Venus). Here’s the lyrics: http://www.kurozuki.com/takeuchi/anime/xmas/omedetou.html The biggest tip-off is that she says ‘hora, Artemis’ before singing.
Re: Yeah… I like truly terrible things like Japanese Christmas Music
Four years later, the mystery is solved! Thanks for the information! I’ll update the post later.
This year I got into ambient and techno Christmas remixes, like this one (it’s an itunes link).