Beebox by Wordbee allows you to take previously translated content and align the source and target files to come up with bilingual files (XLIFF) that can either be reviewed or converted directly into a translation memory. You should only tackle an alignment project if you have files that are highly correlated. In other words the files should have a definite structure with a one-to-one match for the number of sentences. If the source and target language files do not follow the same structure then the results of the alignment won’t be very useful.
This short video shows you how to setup an alignment project using Beebox.
Update: So this is why the guys at Wordbee are awesome. They saw the video and made the alignment process even easier now! At the project level, you can now go to settings and choose Active by default and you no longer need to write the instructions files. Simply drop the source files in the In directory and the target files in the Out directory and you are set!