Another interesting module, Floating block let’s you keep a Drupal block floating on the screen if you scroll lower than its original position. For instance, you can select the last block on your sidebar to remain visible even after the user scrolled down below it.

It is very useful for maintaining important content always visible in the viewport. You can even add a padding to the selected block so you have more control over where the block remains set in the float. Aaaand, it is not only blocks you can float, but even your entire sidebar if you want.

You can select what to float here: admin/config/user-interface/floating-block. But always be careful what and how you float. For instance, if you float the first block in your sidebar, the result will probably be something you don’t want.

But definitely check it out.

Hope this helps.