Routing

Tim Bray wisely instructs...

Even if you’re living on one computer right now, it might be smart to write your integration pretending that you’re not, so that when the load cranks up, you can scale out.

I saw Atanu Ghosh talk about the XORP router project at OSCON last week. This is exactly the approach they've taken, and have been able to move components out to multiple machines. Not exactly intuitive for a router architecture, but a wise choice generally as Tim says.