The thing is that I can't really think of nice metrics like this, and am surprised that a lot of engineers would find something as significant as sales numbers.
For one thing, the further your metric is from strict revenue, the harder it is to put a price tag on it. A sales number is easy, but if you optimized some part of the code somewhere, it becomes much more fuzzy and longer to explain. Sure, Patrick also pushes people to get jobs were your contribution is more directly correlated to revenues, but not everyone will want a job like that, and until you do get one, you can't use that.
The other thing is that I feel it's easier to consider a sales person as directly responsible for a significant increase in revenue for their market. But engineers work in teams, so saying "I increased sales by x%" is hard to justify: what about the Product Manager that spec'ed it out? What about the rest of the engineering team that worked on that change, reviewed it, pushed it to production? If you're the only one doing all that, sure, but that's rarely the case.
So, what's a good way to come up with relevant, justified metrics like that?