There's a new app that offers a crazy amount of information on a device's inner workings, but it's only new to Android. AIDA64 has long been available on PCs, and now you can use it on Android to see what's going on inside your phone, tablet, or even your watch. It'll probably tell you way more than you needed to know.
AIDA64 has a material UI that adapts to both phones and tablets. It splits system information into sections like CPU, display, thermal, codecs, and so on. You can tap on any of them to see what AIDA64 has found about your device. Many of these sections also include live updated stats. Installing the app on your phone will also sync AIDA64 over to any connected Android Wear watches where the app can offer similarly detailed system information.
AIDA64 is available on all Android devices running Froyo and costs nothing. It seems quite impressive.