I have just been sent the IP Pool source.
This is what my friend said:
You start with a range of IP addresses and it lets you allocate from the range. Also lets you subnet ranges that you have allocated. The main class is called IPAddressManager and you can launch it from the command line. It is supposed to work as an Applet but it didn't work when I tried it. It might be that re-compiling will get the Applet to work.
I have not tested this myself either but I'm sure it will come in handy.