In my quest to find even more uses for my iPhone, I stumbled upon Perceptive Automation, the developer of Indigo.

From The Developers Site:

Indigo is a home control server that is compatible with INSTEON and X10 compatible devices, such as light switch modules, sprinkler controllers, and appliance modules, to both control your home and get the status of devices in your home (motion detectors, light status, etc.). INSTEON and X10 compatible devices use your existing home wiring to communicate. You do not have to run any new wires! In addition to having a built-in web server, Indigo also introduces Control Pages allowing the graphical creation of powerful web pages capable of controlling lighting, appliances, sprinklers, and more. Indigo’s Control Page editor allows you to create and edit Control Pages without the need to understand HTML, CSS, or JavaScript programming. Rich AJAX-driven web pages are automatically created providing you a quick way to access, control and receive real-time status of your home.

User screenshots from the Perceptive Automation forum and how they use their iPhone with Indigo:

Nice remote application from IOSPIRIT GmbH for the iPhone reminiscent of Salling Clicker which I used with a Nokia E61.