I got an email today:

Hello Oli!

My name is [withheld], and I’m Sales & Marketing Manager in [withheld]. I found your contacts on stackoverflow.com. We are impressed with your activity on this website. Our company would appreciate if you could help us to promote our tool and services on it.

We would be grateful if you could post a few answers mentioning our company’s name, tool or services. Can this collaboration be interesting to you? Under what conditions would you agree to do this?

I look forward to your reply.

Best Regards,

[withheld]
Sales & Marketing Manager

I've never used their product.
I've never previously recommended it.
They want me to use my established reputation to astroturf their product.

This isn't the first email I've had like this. As a moderator of a SE site I'm curious to know how many people actually respond to this sort of nonsense or worse actually act on it and post on an SE site.

As far as I can see, there's only one passing mention of them on Stack Overflow to date so I don't think they're a problem yet but I did wonder if there was somewhere I should be reporting companies who are trying to spam the site with fake recommendations.