Can I bulk download purchased songs from iTunes?

I've moved my library to an external drive. As a result thousands of my purchases are absent. I know I can go to the iTunes store and download each missing song individually. But ...is there any way to do this in bulk? There are literally thousands of songs and albums and doing it manually is utter torture. I'd pay a small child to do the job but I can't find one dumb enough. Somebody must have hack for this.

[Re-Titled by Moderator]