op commentators widget for blogger with backlinks to there blogs is very nice widget to show of the names of the readers of your blog with maximum comments with the link to there blog.As this can show any no of names you want with most comments. It's plugin was easily available in wordpress blog to install but for blogspot users was difficult to use.
Change the codes above with in red with name of your blog,total no of names you wanna show and Name with any name you want to exclude from the list of yours.
Now save It . And view your blog. It show up the list of the top of your blog with how many comments they have done.Isn't it very easy to add up this widget.