When you build an action at Launch Center Pro, you can access your contacts and grab a single one to enhance your action. Unfortunately, there's no way to interact with your contacts as you run your actions. Mingle is a contact manager for iPhone with custom actions support that allows you to exploit the power of URL actions and complement your use of LCP.
If you haven't heard of Mingle yet, Federico Viticci wrote a nice introduction at the release and Eric Pramono created a series of actions to delegate Due reminders and Fantastical 2 events among your network.
The concept behind Mingle is that you get your contacts and a search bar, you can swipe through a given contact and release when you hit one of your four preselected actions, which are chosen based on calls, messages (via Messages and WhatsApp), emails and the contacts's Twitter handle. You can select what actions will be available in the swipes and also create entirely custom actions.
Call later with Due
This action works because when you mark a reminder as done in Due, it'll check its content for interactive strings, such as phone numbers, emails and URLs, and prompt you for action. The following action will prompt you to insert when you want the reminder to nag you and create a Due reminder using the following string: Call [displayName] [prompt] [phoneNumber]. Thanks to natural language support, you can write in 30 minutes or at 3pm in the prompt and Due will recognize and adjust your reminder in a single tap.
due://x-callback-url/add?title=Call%20[displayName]%20[prompt:in or at]%0A%0A[phoneNumber]
You can add this action by swiping from right to left on Mingle until you open the app settings. You'll find your four actions, which can be replaced. Tap the one you want to change, then Custom Action. Pick a nice icon, a fresh color and paste the previous action in the URL field.
Send emails using Dispatch
One of the first things you want to do is replace your email action to use Dispatch instead of the built-in Mail app. Dispatch recently added x-callback-url and a bunch of new features, standing out as the best email client for iPhone.
If you succeed or cancel your email, Dispatch will prompt you to return to Mingle effortlessly.
Attach actions to contacts and launch them
This is something I can't find a specific use, but if there's someone to whom you often sends the same message or email, then this trick may come handy. If you edit a contact (in the Contacts app since Mingle doesn't support editing) and use an action in the URL field, you can trigger it from Mingle using a custom action with only
[url]. Really, give it a shot and see if you have a situation where this fits. Unfortunately, you can't use Mingle's parameters, such as
[displayName], in the action, yet this expands what you can do with only four actions available.