With WordPress 2.5 being released, the IDs on all admin pages have been removed as it is. Propably due to the fact that the common user dont need them. However, for advanced WordPress Users/ developers those IDs were quite interesting for some plugins or template tags.
What this plugin does is to reveal most removed entry IDs on admin pages, showing the entry IDs, as it was in versions prior to 2.5. Following IDs can be revealed: Posts, Pages, Categories, Links, Media, Users, Comments, Link categories, Tags (WP 2.8 and above)
Reveal IDs for WP Admin Plugin for WordPress Admin Users