Career services for Generation X, especially women. The cohort is about 50 million individuals, mostly mid-career now, and extremely vulnerable to becoming victims of the Internet economy. The youngest X'ers are now 33, and the oldest around 45.

I'd say the addressable market is around the 25-million mark, since even those who have jobs are vulnerable, since they typically have 80s/early 90s pre-Internet era skill sets. Even those with the right skills are too old and financially incapable of participating in the rent-and-ramen entrepreneurial economy that has emerged to help out Gen Y.

The women of this generation are likely to be in the middle of, or just coming out of, taking a 2-5 year break from the workforce for raising kids.

The Boomers are retiring and people are worried about capturing their knowledge, but Gen X actually has (I'd say) about 70% of the knowledge Boomers have, plus their own unique knowledge of stuff that happened during their main individual-contributor working decades. They have between 20-40 years of working life left.

So any idea that takes the knowledge, skills and experiences in their heads and turns it into valuable assets for the Internet age has a lot of potential, while helping them gain income security for their uncertain decades ahead, is going to be very powerful. Examples include:

1. Deep vertical industry expertise for creating the 'Internet of Things'
2. Capturing subject-matter expertise in non-Internet stuff in the form of domain databases and expert systems
3. Services for mid-career professionals to land gigs relevant to their expertise

Full disclosure: I am slap bang in the middle of this generation, and am so damn typical of its issues that it is not even funny.