NInject: Where do you keep your reference to the Kernel?

It's true that you don't want to pass around the kernel. Typically, in a web app, I store the kernel in a static property in the HttpApplication. If you need a reference to the kernel, you can just expose a dependency (via constructor argument or property) that is of the type IKernel, and Ninject will give you a reference to the kernel that activated the type.

If you use WithArguments() on a binding, they will be used for all activations. If you use IParameters, they will only be used for that activation. (However, if the service you're activating has a re-usable behavior like Singleton, it won't be re-activated even if you pass different IParameters.)

This is a common pitfall when starting to use a IoC container. See this related question.

In a nutshell:

• It's bad practice to pass your container around (been there, done that, and it really hurts)
• If you really need to invocate directly the container, first consider abstracting to an injected factory, then as a last resource consider using a static gateway to the container