A couple of Mods I'd like to toss in for you guys. - iChun
It is YOUR responsibility to read ALL the info to prevent any issues.

Advanced Knee Replacements
- Adds only the AKR from the Portal Gun mod. DO NOT have it together with the Portal Gun Mod.

Companion Cube
- Adds the Companion Cube and its records. DO NOT have it together with the Portal Gun Mod.
- You will have to copy the "mod" folder from "place in resources" into "resources" for the records to work.

Portal 2 Addon
- Adds the "Want You Gone" song from Portal 2, for now. REQUIRES the Portal Gun or Companion Cube Mod.
- You will have to copy the "mod" folder from the into "minecraft/resources" for the record to work.
- Sound file format = /minecraft/resources/mod/streaming/portalgun/wantyougone.ogg
- Crafting recipe is crafting 2 "Still alive" records. 
- (Portal Credits Song + Portal Credits Song = Portal 2 Credits Song, geddit?)