Slicer is a new plugin that will make your life easier when setting up assets for export.
It offers presets for Desktop, iOS and Android and you can define your own as well. Setup your slices once and hit ⌘ + E to easily apply chosen export settings to assets.
And as a bonus, the plugin also makes it easier to create 9-patch graphics for Android! Another excellent Sketch resource from Oz Pinhas (@ozzik)