Here are the Maya and Max plugins (latest version 2013.1, the version UE4 uses)
Converter and here’s the stand alone converter.
Most 3d applications should have an up-to-date exporter (Blender 2.7 for example), or the app’s publishers should have a download link. As for UE4 itself, that doesn’t need a plugin since it supports FBX importing from the get go.