http://calibre-ebook.com/
rather than control my library of books on my kindle, which is probably difficult i use calibre on my pc to organize my ebooks. Then all i need to do is plug my kindle into my pc and calibre sees it and can send and delete ebooks on the kindle. It is really useful if you want to get ebooks from other places onto your kindle, although only usually if they are drm free like the baen ones are. One of it's biggest features is that it has the ability to convert ebooks from one format to another e.g. epub to mobi or lit to epub or even rtf/html to mobi; so long as there is no drm on them. I've taken some epub fanfic and converted it to mobi to read on my kindle. Someone has made some third-party plugins for drm removal but i have only used the amazon one (google calibre drm removal). I still remember using the command line program clit on a lit book.