I use MP3 Tag Pro, it allows not only to extract the correct id3 tags from a music file, but if it is missing it can download this information from the Internet. It can also find and download the sonds' lyrics and album covers.
I'm very much satisfied with Movienizer. It supports many movie related sites and not only IMDB, therefore I was able to extract info about each film I have in my quite big collection. I like the navigation system, it's not overloaded and easy to maintain, I like how the categories are arranged and variety of search options.