The one and only phone-finding app that doesn't have to be open to receive alerts!  With "Find My Brain", you can configure a set of devices and the alert sound to play, and then use your Pebble to remotely trigger that alert later.

NOTE: This app cannot override the iPhone "Do Not Disturb" mode, mute settings, or volume level.  To be sure you can locate your phone, make sure to leave your device mute switch off and the volume turned up.

eNotify provides filtered email alerts and, on Android, SMS notifications. Highly configurable, eNotify supports rules with custom alert sounds for different accounts, senders, subjects, recipient addresses, phone numbers and more. Easily silence day-to-day background noise and stay aware of priority e-mails and SMS messages.  NOTE: If you're an Android user, you will likely prefer to use the Android Wear eNotify features, instead of this watch app.