A plugin offering a widget showing recent photos in posts. It can be configured
as for how many photos to show, the title on the widget and max width and height for
thumbnails.
The thumbnails links to the post where the photo is showing. They show a mouse over
effect with bigger version of the photo in a tooptip.
It has option to exclude photos from the view.
It has only been tested with WP 4.2, it might work with lower versions.