Can someone tell me if there is a module that will allow a user to create multiple nodes of different content types within one form? I have a base content type that can have a 1 to many relationship to another content type. I want the user to be able to create the base content type node along with 1 to n nodes for the second content type.
The module you are looking for is Node Reference Create. Here is a quote about it (from the module's project page):
... is an enhancement to the nodereference autocomplete widget that allows users to reference non-existent nodes.
When no matching node is selected, the new nodes are automatically created allowing for a seamless and intuitive user experience that is similar to free tagging.