This is an interesting new app for Android users:

Android addicted? Heavy app user? Need more control over your apps?

AppDetox helps you to calm down your mobile app usage, and take a digital detox. You are able to set your own rules for your app usage to detox from some heavy app usage and stop procrastinating. According to your own rules the use of some apps will be forbidden. You will see temptations when you tried to launch an app against your rules in a log.

Looks like it has an interesting range of options: not only can you schedule apps to stay away from on certain days or the week or times of day, you can set a number of launches, or set a maximum usage time per day.