Versus - Find popular alternatives to anything in a jiffy
Appszito - Appszito is an independent app store over the internet where the smartphone users come to look forward for their favorite apps for free.
Productz.com - Crowdsourced products database
APKMB - APKMB is a website dedicated to MOD APK files of various Android apps.
Kimovil - Compare price, specs, reviews and benchmarks for smartphones and tablets.
APKStone - All apps in one place. Download APK files or from Google Play Store.