Poedit is a gettext translation (.po file) editor for Unix, Windows, and OS X. It aims to provide translators with a simple, easy to use user interface with all the essential tools such as spellchecker or translation memory. It can also be used to manage translations for small projects.
Information regarding Project Releases and Project Resources. Note that the information here is a quote from Freecode.com page, and the downloads themselves may not be hosted on OSDN.