Last night I decided to mod my Galaxy S3 dock (a phone I no longer have) to accept the Nexus 7! Both devices have the usb micro on the bottom center of the device, but the plug is upside down the Nexus 7!
Here's a close up of the dock's connector. The goal will be to rotate this 180 degrees!
And the Nexus 7's connector (Top = front)
To begin: With the dock closed, flip it over and peel off the rubber bottom to reveal 7 screws. Take them all out.
Next, starting from the side of the rock, use a tiny regular screwdriver to split the top and bottom halves apart. There are clips holding it shut so some force is required.
Cool! The dock is now open. We'll focus on the top half - the counterweight on the bottom half IS enough to keep the Nexus 7 upright.
This is where the ribbon cable goes to the top side of the dock, and into the connecter. Doesn't look like we can loosen it from here - so we'll have to dig in.
On the left and right there are 2 tiny screws and 1 tiny spring on each side.
These springs are tiny! Don't lose these! The easiest way to get them off is to use a needle to pull from within the loop at the top end.
By removing these springs and screws we can remove this component - remember to unclip the ribbon cable from the PCB!
There's a sprig loaded cover on the top. Pry it off from either end. Be careful, I cut my finger nicely doing this.
NICE! We can now see the screws holding in the USB connector!
Once you remove the connector, simply rotate it and plastic mount 180 degrees and screw it back in. Remember to completely remove the ribbon cable from the large plastic piece, it rotates as well. From here, it's as simple as following the steps in the reverse order to reassemble the dock.
IMPORTANT: Remember to put the ribbon cable back in it's socket on the PCB in the same orientation it originally was. This means the cable will have a twist in it when you're done.
Unfortunately the Audio out on the back of the dock does not work with the Nexus 7. Perhaps this could be solved though software? Charging, of course, does work.