Homejoy and Exec are the perfect examples of companies that have gone very deep into their one offering, house cleaning. While other companies like Thumbtack and MyTime have gone very wide to gain more marketshare, faster. MyTime and Thumbtack offer every service under the sun. They are creating demand and then finding supply as they go. I am not sure if one strategy is better than the other when it comes to creating a marketplace for services website.
Thinking of a new venture (either startup or a new initiative within a larger company), I would always suggest being focused on a single offering first, but with the following caveats:
1. In my view, the purpose of the first offering is to test the business hypothesis, this means not only offering but: target audience, need, specifics of the offering as the solution, and its differentiation. Really be laser-focused on all of these.
2. The only way to test that complete hypothesis is to develop, in full, an offering for a well-defined target audience, etc.
3. Once it is out and you measure adoption and success, it's critical to assess which of the assumptions are proven to be valid - could be that the need is not strong for this audience, or that there's not enough differentiation - the offering is only a part of it. You can only test this well if you developed a good offering to a well-defined audience solving a well-defined problem.
4. Then - iterate. You may need to change your offering, but you may also discover that your audience has a stronger need (they all email you and ask for it). The key here is "drop" everything and be flexible - now it is time to lose the former focus - you may need to make dramatic changes.
In my experience, companies that went through this cycle (of building a deep offering and then iterating based on the data it provides) have been the most successful.
