Once a hard disk starts clicking there is usually very little you can do.

Companies will charge hundreds of pounds to retrieve the data and even then its not guaranteed you'll get back what you want.

I've heard that putting the hard disk in the freezer for a few hours can help (put it inside a sealed plastic bag first to stop moisture being an issue. This might buy you a few minutes...

What happens if you try to boot it from a Linux Live CD (Like Knoppix)? You should be able to do that on Intel Mac's now shouldn't you?

If you do decide to try the freezer option - research it first, dont just take my advice! (This is a disclaimer!!)

Good luck - please let me know how it goes!