This might be a long shot but I thought I'd throw this on here. Natron is a node compositor similar to Adobe After Effects, The Foundry's Nuke and Eyeon's Fusion. I've yet to try it because I usually work on After Effects. However, since I can't take After Effects with me everywhere I go, I might just switch over one project to this and see how it goes portable.
Binary Downloads here:
Source Download here:
The only downside I see is that it "might" require Microsoft's Redistributable should installing error's out on missing DLLs.
I too would like to see Natron added to PortableApps. The developers offer a no-install download that simply has the program zipped, however the directory structure of the program places the executable in the 'bin' subdirectory, which PortableApps.com Platform doesn't scan.
This has been released for testing: https://portableapps.com/node/57877