This feature is common in many websites, but is most recognisable in the New York Times website.
This module is undergoing active development - if you have any suggestions, please create an issue!
The 2.x branch requires the Regions module. Slidebox now creates a region that you can drop blocks, panes, views, etc. in as you wish. The goal is to be as flexible as possible.
Currently, the 7.x-1.x branch does not work with Panels, Display Suite, and presumably any other similar display management module. This should be fixed in version 2 - see #1372260: Let's make this more of an API and #1153274: Make Slidebox work properly with Panels.
- This module is sponsored by VMdoh.