Ruven

This plugin registers a custom post type for portfolio items and a taxonomy for portfolio types.
Selected themes by Ruven provide templates to display portfolio items. 
In other themes you most likely have to add them by yourself.

Ruven Themes: Portfolio

RT Portfolio enables a "Portfolio" post type and "Type" taxonomy.

OyoThemes

The Zica Portfolio Posts plugin adds a new custom post type ‘Portfolio’ to a WordPress instance. This plugin is spplements the Zica and Zica Lite WordPress themes which utilize WordPress’s custom post type functionality.

Zica Portfolio Posts

The Zica Portfolio Posts plugin is a WordPress plugin that will let you add a new custom post type 'Portfolio'.

Ruven Themes: Portfolio vs Zica Portfolio Posts