I also really like these companies that create new ad-hoc employment marketplaces

For example, JustAnswer is a company that lets random people post questions on a variety of topics (from auto repair to programming to relationship advice). The questioner specifies how much the answer is worth to him. Then the question is posed to the community. Whomever answers the question in a way that satisfies the questioner gets paid.

Similar to lots of other efforts to "crowd source" resolution of various questions. Major difference (with JA) is that the answerer gets remunerated (i.e., paid for his trouble). Another major difference with JustAnswer in particular is the amount of due diligence they do in order to "certify" various folks (potential answerers) as being Expert-level in some category. The idea being that if I ask a question about an area I don't know much about, I can rely on JA's accreditation of folks as a gauge of who is trustworthy. I took their test to become certified as an expert in programming and found it reasonable: 10 multiple choice questions, not cake, reasonably generic (rather than w.r.t. specific idioms/languages/paradigms).

But basically I am always really pumped about products that create opportunities for small-scale entrepreneurs to run their own businesses — whether that business consists of answering questions (using JA), writing apps for the iPhone, writing apps/games for Facebook (or some other social network), etc.

We also saw this with Coghead awhile back which let individual coders (or small teams thereof) create applications on the Coghead platform and then sell those apps as a service to whomever. So an individual programmer becomes in effect a SaaS provider by leveraging the Coghead foundation. Of course we see something similar with AppEngine — where Google worries about hosting, server administration, and so on. All you have to do is create your Web service (in Java or Python) via providing code to execute when particular URLs are visited and you're off to the races.

The whole thing results in a lot more liquid, task-specific employment market — and gives workers a lot more options. In a way it's not different than the advances we've seen in resource management in computer science. Fueling the resurgence of virtual machines the past decade was the fact that companies had servers that were not being used wisely. Might have a dedicated server for each different service (e.g., mail, web, news, ftp, ...) which resulted in poor resource allocation because some resources sat idle much of the time while others were (at the same time) oversubscribed. With virtualization, resource allocation became more fluid. A high-demand service could be spread across machines whereas quieter (lower demand) services could all safely share the same hardware without adversely affecting one another.

In any case, I'm way bullish on any company or product that encourages this same "efficient resource allocation" of human capital. Develop a more just-in-time marketplace where matching humans to jobs occurs dynamically and in response to real-time demand. Taking the real-time per-impression ad-auction paradigm and applying it to humans and jobs/work to be done.