As we (well, mostly other people than me) were dealing with a rather obscure micro-controller when hacking our laser projector in brmlab, the only datasheet we have found has been in Chinese. This is quite often the case with obscure China-made parts (including event stuff like LEDs) and it’s annoying to deal with.
So I hacked together a simple datasheet translator – you feed it a PDF with your datasheet, specify the source language, let it munch away for a minute and then it spews out a link to the English translation!
Its user interface is extremely rudimentary, if someone wants to add an AJAXy progressbar and what-not, just let me know. :-)
The “technology” is not much to mention either – thankfully, pdftohtml can do quite nifty stuff nowadays (just needs a lot of beating to properly zoom the documents), and Google Translate can do awesome job with technical documents.