I'm finding that all android devices are different and you have to be very careful when you choose your device. On Boxing Day (the day after Christmas) I bought a Google Nexus 7. This is a nice 7″ tablet with a clear screen, reasonable battery life and it has a micro-USB, but no camera.
I have also been looking in my local stationary store, they have 7″ tablet but this one has a different USB port. They also have a Samsung 7″ tablet that uses the proprietary Samsung port. So none of the cables are interchangeable.
I recently found a very cheap 7″ tablet online. It uses a micro-USB port, like the Nexus, but the battery life is shocking, just over two hours. It doesn't have a glass screen like the nexus and iPad. It has a front facing camera, which is only good for Skype. It came with a connector cable that I could use to connect a USB flash drive to it, and play movies directly from the USB.
The Nexus 7 has a good battery life and a nice screen, but it does not have a camera, which disappointed me. I recently got a USB connector for it, but unless I root the Nexus, I can't access files from a USB flash drive. And it has no HDMI output, so I can't connect it to a big monitor.
The Samsung tablet is the most expensive of the tablets (not including the iPad) that I looked at. It has a camera, it has HDMI output, but you have to buy the proprietary cables to connect it. Until you get to use one for a few days, you can not find all the small things, like the connection to flash, the movie formats that it doesn't play and so on.
Before you buy one of these devices, do your homework. They are not all the same, they do not have the same connections, outputs, camera, or battery life. You could buy a cheap tablet like I did, then find that it is a waste of money.