Tags on Amazon and folks agreeing with them are essential to any author to ensure their books actually turn up in searches.
However, the painful point about tags is that tags are unique per instance of a book, per amazon site, thus, not only do you have to put tags in for each instance of your book, so if you have multiple formats, they are unique per format, but when someone agrees with one tag on one instance of a book, that doesn't help the other instances on other sites.
That said, I need folks to agree with my tags, please, so if you happen to be on amazon, any of them and fancy taking five minutes out to agree with the tags on my books, I'd be very, very grateful. :D
Sophie Duncan on Amazon.com
Sophie Duncan on Amazon.co.uk