The Acer W510 doesn't come with a full size USB port on the tablet, as mentioned previously Acer has provided a USB Micro to USB port (ie. USB OnTheGo) cable in the box. But when you're mobile you don't want to have a cable dangling around no matter how small a thumbdrive you're connecting it to.
Knowing that it might be a problem I looked around for a solution and found this.
It's basically a solid USB OTG plug, it's also set at an angle so it doesn't extend outwards of the W510 much.
The W510 is a bit thinner than the plug itself, so it's not going to lay flat when this is plugged in. The fact that it's pretty close to the body *might* cause some problems with extra fat USB devices though.
I bought these from Deal Extreme, they come in a pack of 2 connectors. One in each direction
So one will point towards the top, and the other point towards the bottom of the W510.
Highly recommended if you want to have a more mobile, less dangling experience with the Acer W510. You can grab them here. (affliate link)