FileBot

Tool for renaming media files so they are better scanned by XBMC scrapers (among other uses). Launched via Java Web Start, so no manual download or installation required.

FileBot is really smart about matching your episodes with online episode info from sources like TVRage, AniDB, TheTVDB or movie info from OpenSubtitles and TheMovieDB. The naming format and folder structure FileBot will apply to rename your media files is extremely powerful and customizable but at the same time really quite simple.

Fetching subtitles has never been easier neither. FileBot will automatically lookup subs from various sources and intelligently match them to your media files. Just drag your files in and FileBot will do the rest.

The GUI is extremely efficient, it's all just a matter of 2-3 drags/clicks. But if you're the really lazy kind, you can automate just about anything using the fully-featured cmdline interface.

Official website, forums and downloads:
 * http://filebot.sourceforge.net/

Video Tutorial: