Commerce Bulk Product Creation was the first contributed module to the commerce project and provides a quick way to create multiple combinations of products with a single form submission. It also optionally manages the creation of the display associated to the product variations in different ways such as generating a display for each product created in bulk.
Some conditions in the product configuration need to be met in order to use the bulk creation feature, you need to have one or more fields of list type, boolean or term references with the submodule for taxonomy support. There's also support for Entity Reference fields with the BPC entity reference module.
Note that once created, this module doesn't support yet bulk edition or deleting, you may find useful Commerce VBO for that purpose, but that belongs to other Tuesday's overview.