VidCoder is a DVD/Blu-ray ripping and video transcoding application for Windows. It uses HandBrake as its encoding engine. Calling directly into the HandBrake library gives it a more rich UI than the official HandBrake Windows GUI.
Requirements: .NET 4.0
Since 1.4.16 Beta, you can now edit 2 config files to specify where to save app settings. Specifically, 'VidCoder.exe.config' and 'VidCoderWorker.exe.config'. The line you need to change is commented so its hard to miss. Portable mode should look like this:
<add key="SettingsDirectory" value="." />
Handbrake is a popular media encoder but it's not portable. This alternative gui is kinda portable in the sense that it can have its settings stored in the application folder but it still requires .NET framework.