Android: Every app on your phone already has built-in settings; App Override is a utility that gives you even more control over the apps you use. You can increase and decrease font size, set the screen orientation on a per-app basis, and change the screen timeout, with individual options for each app on your phone.
App Override also lets you set minimum and maximum CPU speed for each app. You can tell an app only to function over Wi-Fi, which is particularly useful if you use data-hungry apps. Best of all, you can adjust these settings on a per-app basis, so your news reader has huge print that's easy to read, and so your video player and camcorder apps are always locked in landscape mode. You can tell your favourite game to use more of your CPU, and then tell your Twitter app to stop gobbling down resources at the same time.
App Override doesn't require root to install, but if you want to tweak CPU utilisation, you'll need to be rooted. All of the other features can be used if you haven't rooted your phone. The app is free and in beta (so expect some bugs here and there), but it works well. Hit the link below to grab it, or head over to this thread at the XDA Developer Forums to read more about it.