Large number of devices

I have a rather strange question. I've googled for a bit and haven't found anything. I'd be happy to read any books recommended or look at any sites recommended if that would help. Is there any techniques, ICs, etc that are used to interface a microcontroller with a large number of devices, such as 512 or 1024? I've been looking at I^2C for a bit and borrow some books on the interface. I like it. It provides addressing of up to 127 different devices in normal mode and more using the extended addressing. However, with this, it appears there would not be any way of having any of the devices "contact" the microcontroller, unless of course the device become an I^2C master and the entire circuit became a multi-master circuit. Are there better ways to handle this? I'm not always great at explaining things in a post, Ill clarify anything that needs clarified if need be. Thanks.