For all bloggers out there, you might be familiar with this widget. You might be using it right now, or you're not. Well, if you are interested, read on.
Enter your email address.
Enter the url of your blog.
Select your blog platform. Options available are Blogger, self-hosted Wordpress and TypePad. If your blog platform is not listed, select other.
Choose your desired width or story panel needed. Options are 3,4 and 5 widths.
If your blog are using dark theme, tick on the box with "My blog has light text on a dark background" label.
Click Get Widget to proceed.
Follow the steps shown to add the widget to your blog. Finish!
Just a reminder, to use LinkWithin for 2 or more blogs, repeat all these steps here.
Update: You might also want to check nRelate plugin here.