I used to live by this program:
It gave you detailed tag info of files with the 'pop up box' that appeared when you held the mouse pointer over a the file in Explorer for a short time. This is the feature that I found most useful, but it also provided the ability to look at and edit tags in Explorer through the properties option on the right click menu and also, if my memory serves me rightly, extra shell column options within Explorer.
However I have now changed to 64bit Windows 7 and the program has not yet been updated to work with it and I'm not confident it will be updated soon or that someone else will write a program like this soon.
You can get these functions with dBpoweramp, but you have to pay for dBpoweramp and as the main function of the program is ripping and converting, this is where your money is going really. I'm not interested in the ripping and converting.
It would be marvelous if mp3tag could be extended to provide these functions.