Heya
Most of the Apps that I use frequently appear to have already been made portable.
Foobar2000 is one of the two that I find missing.
As Foobar2000 already has an option during installation to be installed onto a portable device, I believe it should not be too difficult to make this into a PortableApps.com installable.
Available at:
http://www.foobar2000.org/
"foobar2000 is an advanced freeware audio player for the Windows platform. Some of the basic features include full unicode support, ReplayGain support and native support for several popular audio formats."
I really would like to see it in a PortableApps.com form too. It's the only audio player I like.
Already made a launcher for this.
https://portableapps.com/node/21037
Pretty straight forward, just follow the instructions to install. I don't think it's perfect yet but it certainly works for my needs. Foobar2000 has a portable mode install natively (which is used for the launcher installation) so you might want to check that out too.