Here is Portal Core - a megamix I put together of various Portal themed songs and remixes. I contacted every artist for permission to release this video. Many said yes, a few didn't respond, but none declined so THANK YOU to everyone involved. Especially Valve and Portal (this is not with Valve's permission but I'm hoping they're cool with it). 

Go buy Portal from Steam - http://store.steampowered.com/app/400/?snr=1_7_7_151_150_1
And Portal 2 - http://store.steampowered.com/app/620/
http://www.thinkwithportals.com/

The video itself isn't anything spectacular though there's lots of references to spot. But it's better than a static image with just the music playing!

Here is the track list with links:
Supermatty - For Science http://www.youtube.com/watch?v=JuAjkF2IY_U
Alex23 - How Have You Been http://www.youtube.com/watch?v=k4OT7qQgQAQ
Teeku - Glados Portal Remix http://www.youtube.com/watch?v=e6QpYaygHmA
PARANOiD DJ - Want You Gone http://www.youtube.com/watch?v=jbow-fy-g2g
Tansunn - SPACE http://www.youtube.com/watch?v=IBT_d_o2EDQ
Eddache - Through The Portal http://www.youtube.com/watch?v=8Oqku-x5pdg
DJ Almix - I'm Gonna Burn Your House Down With My Combustible Lemon http://www.youtube.com/watch?v=ifOpg_SSWos
Risuno - Combustible Lemon http://www.youtube.com/watch?v=E7uFXLszM1E
2-Byte - Target Lost http://www.youtube.com/watch?v=WvWqrsD2Cus
Miracle Of Sound - Wheatley's Song http://www.youtube.com/user/miracleofsound / http://www.youtube.com/watch?v=obV5Ws8WTec
Victims of Science - The Device Has Been Modified http://www.myspace.com/victimsofsciencegxp
Oggycheese - Hip Hop Glados http://www.youtube.com/watch?v=ttP1B6sKr-E
JB Garren - Good Enough For Science http://www.youtube.com/watch?v=7jLnwJv8Vqc
Brainforce V - Why Wheatley Why http://www.youtube.com/watch?v=C4KLv8Iuv7E
Gryoss (SORRY I MISSPELT YOUR NAME IN THE VIDEO ARGH!) - Cara Butts Turret Opera Remix http://www.youtube.com/watch?v=pspp0nzzB7U
Raddox - Still Alive http://www.youtube.com/watch?v=sLKKYbADEYk

The megamix can be downloaded here: http://soundcloud.com/eddache/portal-core