OmegaT is a free translation memory application written in Java. It is a tool intended for professional translators. It does not translate for you! (Software that does this is called "machine translation", and you will have to look elsewhere for it.) OmegaT has the following features:

• Fuzzy matching
• Match propagation
• Simultaneous processing of multiple-file projects
• Simultaneous use of multiple translation memories
• External glossaries
• Document file formats: plain text, HTML, OpenOffice.org/StarOffice (the latter has excellent conversion filters for MS Word, Excel, RTF)
• Unicode (UTF-8) support: can be used with non-Latin alphabets
• Compatible with other translation memory applications (TMX Level 1)

Note: While the software is classified as free, it is actually donationware. Please consider making a donation to help support development.