iOS Jetpack - Beautiful easy-to-use screenshot templates for App Store
Radix Icons - A crisp set of 15×15 icons. Open source.
App Screenshot Maker - Design marketing screenshots for your app in minutes
MakeAppIcon - MakeAppIcon resizes and optimizes your icon designs into all formats needed for iOS and Android mobile app!
Promomatic - Easily create beautiful app store assets
Ayecon - Ayecon is an app that allows you to easily make icons according to the required dimensions.