Injecting Collection of Classes with Guice

What you want for this is Multibindings. Specifically, you want to bind a Set<Action> (not a List, but a Set is probably what you really want anyway) like this:

Multibinder<Action> actionBinder = Multibinder.newSetBinder(binder(), Action.class);
actionBinder.addBinding().to(FooAction.class);
actionBinder.addBinding().to(BarAction.class);

Then you can @Inject the Set<Action> anywhere.