You do not need a network.  You can do it with only one XBee.  To get to Command mode send "+++" with time before and after.  Then ATED.  The serial text results are easy to parse.

http://www.sparkfun.com/datasheets/Wireless/Zigbee/XBee-Manual.pdf

Can I see a parts list for Mini-uino please?
If you could include a link...

My point, and question, is whether it is easier to use the constant heading formula for a long distant traveling robot?
Of course it doesn't matter for short distances.

I found one in the middle of the ocean last year, 200lbs, 8ft long.
A foam boat with a powerful motor and solar cells.
I guess it's not hard to implement so that the heading changes as you go.

For humans it's easier to look at a compass with a constant heading,
and it uses less battery power!  If you don't mind the scenic route...

Great price compared to 5 years ago!
Perfect for sailors...

Or you can use the other formula for a constant heading. 
For short distances this will be the same number.

At longer distances the distance traveled is significantly more.
The formula is about as long to calculate.
But it's easier to navigate with a compass if you're sailing.
How about a robot with a magnetic compass?

Pro version.  1/2 mile thru the woods.  1 mile line of sight.  3-4 walls.

I gotcha.  If the Leonardo only comes with HID drivers, then you cannot attach it to a mobile phone or a GPS or a scanner or even an HID slave device.  AFAICT you can only use it with a PC.  Which of course must be nearby.  For me personally I don't see the point.  I hope someone will start building other drivers soon!

Someone would want to emulate an RFID reader?  Instead of plugging it in directly to the PC?
We agree then, there is not much practical use for it...

Not anything.  It has to be an HID?

Is there a library I can use with RFM70?
Code?

In my experiments I still had a good data rate even when RSSI was at a minimum.
IE It can be used to measure short distances only.
Instead try measuring the RF energy level using the ATED? command.
Or retries.
Or data rate.
Want a snipped of code?

Could someone please specify the alternative which is faster? 
Of course it depends if you need to create the file first...

I agree.  Done.  Asked.

So it can be used to sample audio?  I have a simple FFT sketch that works with this circuit:
http://www.datasheetcatalog.org/datasheet/analogdevices/SSM2166S.pdf

The $5 Mic is an alternative?

I want to understand what is coming our way...
The Leonardo will act as an HID Slave?
But not an HID Master like CircuitsAtHome USB host shield?
What can we use this for? 
Besides automating a mouse and keyboard to a PC?

Why is the example on Ebay for the $5 module only to measure sound energy level?
Can it also record the waveform?
Assuming a place to put the data...