For the longest time, I've had clients that have wanted to download my application for use on their systems. Part of the reason I created a web service is so that I don't have to concern myself with platforms other then the one I run on.
I've been thinking about buying Zend Encoder to protect my application. I like the fact that it has a license system and you can protect your intellectual property, even remotely. Maybe I'll continue with my SaaS business model and forget all about this download and software distribution non-sense.