Nelson Wolf recently published a blog post to introduce the new FinalBuilder action he'd developed. The action checks that all required variables for a project are available at run-time. Quite a handy action if your projects include a lot of subprojects. You can download it from launchpad.net.
He's also created and made available example projects and a 'unit testing' project for the action.
I have to comment on one other comment in the post that gave me a good laugh.
"Initially I had resisted [FinalBuilder] because I thought it might be too easy."
We've previously heard from devs who are hesitant to try a visual tool because of fears that it may restrict what you can automate, but I've never heard of someone avoiding FB because it might make automating builds too easy! 