I need to create a reusable component that would only be used by other developers within a single SalesForce organization. The component is made up of VisualForce pages and Apex code. I believe this would normally be done as a managed package in ISVForce, but my understanding is that ISVForce requires additional reviews and this package is only for internal use - it shouldn't be listed on the App Exchange.
Is there a notion of managed packages for internal reuse? Or is there some other way to create distributable, closed-source packages?
You can simple create a managed package and install it to your org via install link, this way do not require security review because you do not need to publish your package in AppExchange. Just read a manual about creating managed package. I do believe that a creation of managed package without publishing in AppExchange is pretty simple and straightforward and that's what you really need