Here’s a great app that can actually save you a decent amount of cash. Onavo is an app for iPhone and Android devices that is a watchdog for other apps. Basically, Onavo checks out which apps are running — and which of them are using your data. It reports back to you with what it found – make a few changes in preferences and you’ll stop the flow of costly data for apps you’re not currently using. Here’s how Onavo describes their product: Onavo puts smartphone and tablet users in control of their mobile data usage. Using compression, simple reports and basic tools, Onavo helps smartphone users get the most out of their data plan, without complication or effort. As the only consumer-focused data management app, Onavo takes the worry out of using smartphones at home or abroad. Big name sites like Mashable, BBC, TheNextWeb, and many more have pushed Onavo as a great way to save you cash, so give it a try and let us know. A good friend of mine tried it out last month and saved $31 on her usual data expenses, without changing her browsing behaviour. Get in there!