Self-promotion of products or services is acceptable, if it is directly relevant to the question.
Per our FAQ:
May I promote products or websites I am affiliated with here?
Be careful, because the community frowns on overt self-promotion and
tends to vote it down and flag it as spam. Post good, relevant
answers, and if some (but not all) happen to be about your product or
website, so be it. However, you must disclose your affiliation in your
If a huge percentage of your posts include a mention of your product
or website, you're probably here for the wrong reasons. Our
advertising rates are quite reasonable; contact our ad sales team for
details. We also offer free community promotion ads for open source
projects and non-profit organizations.
If you see self-promotion that does not directly answer the question (e.g. "How can I help my child's gas pains?" receives an answer of "As a pediatrician and nutritionist (here's my website: www.hire-me.now), I suggest you stop feeding the child beans."), then by all means either vote it down, edit it, or flag it for a moderator (or, if you feel particularly strongly, do all three).
If you see a string of valid, relevant answers that seem to indicate a pattern of targeted self promotion, flag one of the posts and explain your concerns to the moderators. We do make an effort to police this sort of behavior, but it never hurts to bring it to our attention.