- Add Indigo to the Action Type list - you can use bonjour to auto discover servers (like you do for the WeMo) on your local network (and you could add the prompt for authentication credentials there rather that in every action). This would allow you to discover Indigo Devices and Actions and users could just select the right one rather than typing in the URLs.
- Barring that, allow an existing action to be duplicated - that will make it easier to create new actions based on existing ones with much less typing.
- Change the button titles: Add Action/Update could be Save, Back could be Cancel. This would help reduce confusion.
I'm sure others will have plenty more. I look forward to see where you're going to take this!