Display the certificate used to sign the APK: keytool -list -printcert -jarfile app-release.apk
Display how each APK file is signed: jarsigner -verify -verbose -certs app-release.apk
Display certificate information: keytool -list -v -keystore yourkeystore -alias youralias
Display some of the info around how the APK presents itself: aapt d badging app-prod-release.apk
Decompile an existing APK: apktool d app-prod-release.apk (see: https://code.google.com/p/android-apktool)
Get the SHA1 value from a certificate (replace approrpiate values): ex: keytool -list -v -alias androiddebugkey -keystore ~/.android/debug.keystore -storepass android -keypass android