Dennis Ploetner

Display a recent posts-widget of all your posts in your blog-network which have a specific tag, category or any other built-in or custom taxonomy.

Multisite Taxonomy Widget

List the latest posts of a specific taxonomy from your blog-network.

Ross Cornell

This plugin adds a simple widget that allows you to display a number of recent blog posts from a specific category. You have the options to choose a title, category, number of posts and whether or not to show the post date. The posts will be ordered by date just like the default Recent Posts widget included with WordPress.

very easy to use

Very usefull

Just like the default Recent Posts widget except you can choose a category to pull posts from.

Multisite Taxonomy Widget vs Recent Posts by Category Widget