Had a question on how to do this from a customer today.
It is possible to create very many cloud servers in a quick time something like:

#!/bin/sh
for i in `seq 1 200`;
do
nova boot --image someimageidhere --flavor '2GB Standard Instance' "\Server-$i"
sleep 5
done

So simple, but could build out many servers (a small farm) in just an hour or so:D

Update

So my colleague tells me, that backticks are bad, i.e. deprecated. Which, they are, and I expected to hear this from someone, as my knowledge is somewhat a little old school. Here is what my friend recommends.

for i in {0..200}; do
nova boot --image someimageidhere --flavor '2GB Standard Instance' "\Server-$i"
sleep 5
done