Corral от Sebastiaan du Toit

I recommend pinning the extension to your toolbar for easy access.

Basic workflow:
Hold down right mouse button -> drag marquee tool over links (can be completely or partially covered) -> release right mouse button to process links and open first batch -> click Corral icon to manage links (open new batches, or clear your queue).

Batches:
You can adjust how many links are opened per batch on the extension's popup menu. The first batch is opened immediately, subsequent batches are queued and wait for the user to click the "Open next batch" button.