Precisely!
Just like domaining - the guys with the vision to buy the best names (and stand the renewals and hold the names) several years ago, are at the top of the heap.
So this gives us some focus - what we are looking for, is probably attachted to a new technology; not a new technology in itself, but something that the technology relies upon. Some examples of this are;
Internet - domains
Cars - fuel
Mobile phones - batteries (actually, airtime is a better example)
While the majority of people are concerning themselves with the primary item, there are (initially) quiet fortunes to be made in the secondary items.
I can see that selling gold with MMORPGs and so on, is similar, but there is too much wrong with it - one of which is the dubious legality, another the potential shelf life, and yet another is that the games are not reliant on it.
This is a good discussion, lets keep the ideas flowing...
We can look at new technology but we can also look at what are the global trends driving new technology.
1. Ecology/sustainability - everything is going green
2. Mobility - everything is going wireless
3. Consolidated - devices are getting more multi-purposed (your PC will be your TV will be your PC. Play games, check emails, watch porn, make calls from your mobile device. etc etc.)
4. Information - always increasing, and better ability to store and transfer it
5. Power - more developing countries, more people, need more power
Besides just the properties you named such as low barrier to entry, etc, lets formulate a better understanding of what the core of the domain business is, fundamentally, in a nutshell, and maybe we can discover where that same opportunity exists in other areas.