I openly admit it in the answer that I am a developer working on the (free as in free beer, closed) software and almost always point to alternatives as well.
Sometimes, the best way to do things is to just use our software and I mention it. I am asking this question largely because a regular user in the field accused me of marketing my company's software. I admit that some of my colleagues have been over-exuberant and have been sent to the penalty box, but I have always tried to keep it clean.
But it would be nice to have a look at stackoverflow policy on this and see the dos and don'ts. If there is none, what would you prefer, as user / contributor, in this regard ?