So many internal networks use the same IP ranges, usually the default subnet of the firewall or router serving the network, such as 192.168.1.0(/24) or 10.0.0.0(/24). At home, this isn't a problem, but when you're trying to connect networks together with VPNs, this becomes a nightmare. So, I present to you, a random subnet generator. Below are ten random network addresses you can use for your own networks, and because they're random the chances of clashes are massively reduced. Bookmark this page and next time you're setting up a new network range, come here and pick yourself a random one.
For anyone who is interested, you can view the code that generates these addresses in the source of this page (written in JavaScript and JQuery).