I don’t mind drop-down menus. They give designers and information architects options for using screen space wisely. But I think many sites do themselves a disfavour by using them in an inconsistent manner.
The popular travel site Carnival Cruise Lines is a perfect example of what I’m talking about. I love the design of their site. For a travel website, it’s very good; it’s clean, and professionally designed. But I have one small problem with their drop-down menus.

Being a big baseball fan, I find myself perusing
Here’s a nice lesson for web app designers and developers, to help streamline the user’s progress when interacting with your application.
There are some cases during the user experience where preloading content is not a good idea.