dotSUB is a browser based tool enabling subtitling of videos on the web into and from any language. There is nothing to buy and nothing to download.
Jubler enables you to create and translate subtitles for video files.
Subdownloader is a Free Open Source tool written in PYTHON for automatic download/upload subtitles for videofiles (DIVX,MPEG,AVI,etc) and DVD's using fast hashing.