The bulk stock management extension gives you a new interface (found in Products > Stock management) which lists your products and variations along with their stock properties.
Products can be filtered by product type, stock management status and stock status, and ordered by name, ID, SKU or stock quantity.
Via the input field you can easily set the stock quantity for multiple products at once. There are bulk actions for setting the stock status too.
Finally, there is a ‘View stock report’ button which lets you print a report of all stock levels in your store: