I was wondering what mega menu's for drupal 7 that allow view blocks to be inserted? Currently I only know about xo mega menu, but i was wondering what other ones do people use or other workarounds you might have for putting in view blocks into drop down menus.
You can use Menu Attach Block module to render block as menu.
Menu Attach Block allows you to attach blocks to standard core Drupal menu items. This is especially useful for creating complex dropdown menus and mega menus.
Any block can be used, including blocks generated by other modules. Blocks generated by Views are particularly good candidates for embedding.
There are quite a few modules that allows you to built megamenus which allows you to insert views blocks.
Other than what bala have mentioned above following are the modules which worth a try.
Menu Views It can be integrated with superfish, nice menus and menu block modules.
TB Mega Menu It has a very nice UI and mobile menu built in.
MuchoMenu This module allows users to create mega menus that have mini panels as their flyout content. The benefit is that ANY type of content or UI can be added to the menu flyouts.
This also has Drupal 8 version for it aswell.