The USB host function on recent Android phones and tablets, is perhaps the most unspoken yet incredibly useful innovation in recent mobile device development. I remember, a few years ago some developers struggling with connecting a 3.5" HDD to an HTC Touch Diamond, and see where we landed now: manufacturers are slowly building the USB host function into their phones and tablets. The Samsung Galaxy S2 and Galaxy Nexus were said to be able to host any USB device as long as it doesn't require any special drivers- so any flash drive and hard disk should be able to connect with those phones. But the USB Host functionality didn't work at all.

It took Google another update to fix this issue, but many users already reported several problems from crashing applications to not being able to connect a USB flash drive to it. As XDA Senior Moderator Chainfire ironically says:

There are even cases where OEMs advertise USB host support, but the device does not support it at all. It appears as if USB host support isn't tested by Google or the OEMs when they push out new firmwares and devices at all.

His solution: a tool which diagnoses the USB host functionality on your phone. It basically gives answers to the question: 'Does my phone have that awesome USB Host function or not?' What you do need is a USB OTG Cable, a simple flash drive and Android 2.3.1 or newer. Results of the app can be uploaded to an online database - so soon we will have a clarifying list of devices and ROMs and their USB Host capabilities.

Take a look at the thread to download the tool and join the discussion. The apk should not be redistributed.