If those projects are looking for a new home, we'd be happy to welcome them at GitHub.
In terms of PortableApps.com, I don't think we'd be a good fit for GitHub since we're a project that's a conglomeration of apps made portable (for USB and cloud use). I think we're around 90TB of bandwidth for downloads in the last month for our open source apps via SourceForge (some of our open source apps the publishers self-host like Inkscape and LibreOffice so we don't push those through our SourceForge project).
Surprisingly expensive business.