I forgot to buy the mini-A USB cord when I ordered my Beagle Board and
instead of waiting another 3 - 4 days to get one in the mail, I
decided to make my own using an extra mini-B USB cord I have lying
around.
If you're like me you'll have several extra USB cords laying around
the house with the mini-B connector. The only difference with "A" is
that the 5th pin (ID pin) is grounded. Even better, the 4th pin is
ground, so you just need to connect pin 4 and 5 together.
Here's the bad news:
* The 5th pin is "floating", meaning that it is not connected to any
wire in the cord.
* A conductive pen has too much resistance to be effective. The 5th
pin needs less than 10ohms of resistance to ground to be effective.
So the only solution is surgery. Be sure you're NOT doing this to a
USB cord that you've become attached to or that has any sentimental
value -- it's very likely you will completely destroy it in the
process. It's good if you have 2 cords, one for practice and the
second for when you destroy the first. 
This should only take about 30 minutes to complete. I'll post
pictures of the process soon.
Tools:
* Sharp knife. (A hobby knife works great)
* Pair of pliers to hold the USB plug. (This saves your fingers from
a runaway knife blade)
* Small slotted screwdriver.
* Short piece of STRANDED wire. (more on this later)
* Super glue (optional)
* Shrink tubing (optional)
Process:
a) First look at this picture and identify where the 5th pin is on
your USB plug:
http://upload.wikimedia.org/wikipedia/commons/c/c2/Types-usb.svg
1) Remove the rubber housing around the mini plug. Hold the mini plug
on it's side with the pliers and use the knife to cut down the seam of
the housing. Do this for both sides of the plug. Don't cut past the
metal plug casing.
2) Pull back the rubber exposing the metal plug casing. Usually the
rubber is poured and molded around the wires, so don't cut or tear
back too far where you could break the wires.
3) Cut the housing flaps that you've just pulled back at the end of
the metal plug casing.
4) Use the slotted screwdriver to remove the metal casing from around
the plastic part which holds the pins.
5) There should be a gap between each of the pins here's where the
stranded wire comes in. You need to tie the 4th and 5th pins together
with a couple strands of wire. Strip the stranded wire and pull out 2
strands. Bend them in half and carefully put them around both pins
and then twist them tight on the other side to hold them.
6) Use super glue to secure the stranded wire "tail" so it wont move
around.
7) Now put the metal casing back over the plug and, if you want, add
some heat shrink tubing around the base to replace the rubber you
removed.
That's it, you should now be able to connect your Beagle Board to a
USB hub as the host.
I used this page as an original guideline, but then altered the
process to be easier:
http://www.oesf.org/forum/index.php?showtopic=22308
Enjoy.