Related Posts Widget
Adds a widget that shows posts related to the current post based on tags.
Tag Plugin: Related Posts Widget
Same but Different – Related Posts by Taxonomy
Display related posts based on common categories and tags.
Pro Related Post Widget
Pro Related Post Widget plugin.dynamically show related post according to post.
IGIT Related Posts Widget
A related posts widget. Related posts show by matching category and tags.
Relative Posts
With the Relative Posts plugin widget you can show up on the sidebar a list…
WP Related Post With Pagination
Allows you add latest post widget in your sidebar with ajax pagination & customizable template.