I ended up going for DVDAttache which is a Java app, it's not too bad. Using its combined Amazon and IMDB search I managed to rifle through my entire collection in about half an hour. Yeah some of the tags might need a little tweaking but it's a start. At least I could take the data from it and use with something else later.

Attached is a screenshot running on Linux, there is also a specific OSX flavoured version which I'll have a go with next time I go downstairs....