Recently, New Scientist (with the Royal Academy of Engineering as competition partner) started a poll/competition where readers could send in a brief statement of what they thought would be the 'nex big thing' in engineering. The question was 'Which technology do you think will have the biggest impact on human life in the next 30 years?' After sending in a proposal, it was up to the votes of the New Scientist readers.
There were many entries, ranging from improved nuclear power to quantum computing (see all entries here). The five shortlisted ones (in no particalur order) were:

Synthetic Biology: Genomic tweaking and global change
From the production of polymers, chemicals and biofuels to use as biosensors or even computer components: the engineering of microbial genomes and the complex biochemical pathways extending from them will have far-reaching implications. The bacterial conversion of cellulose into ethanol may end our dependency on fossil fuels, while the expense of drug production may become limited to the cost of maintaining a fermenter and raw materials to grow the engineered microbe in, making medicine cheaper worldwide. I believe the very big changes about to happen to our world will begin with the engineering of the very small.
Remote sensing and presence
In the next 30 years the user's sense of realism when employing digital connections will converge on the sense of actually being there. Control of a machine on location will add a sense of presence. In effect, geography will increasingly lose meaning. This will have profound implications for our way of life, particularly on commuting and travel. Furthermore, locally there will be significant economic and legal ramifications. Internationally, change will be slower, but the nation state is in fact a geographic monopoly and will be challenged by this development.
Nanorobots fight the medical battles of the future
Say the word "cancer" and people are fear-ridden. Projects being undertaken to harness nanotechnology and develop nanorobots to enter into the human body and repair cancerous cells, without the need for life-changing, disfiguring and painful chemotherapy, will have the greatest impact in the next 30 years. Watching loved ones suffer will be a thing of the past as the robots aid speedy recoveries, mortality rates drop, and as the technology is used more frequently, so will the cost, that oft deciding factor. An enormous step forwards for all mankind, in the form of a microscopic creature.
Machine translation unites the human race
The development of real-time automatic voice translation systems. Because for the first time in human history it will be possible for people from all countries to naturally and easily communicate with each other, without any barriers. People that were previously isolated within their own cultures will be able to understand and enjoy the cultures of many other nations. No longer will people speaking different languages misunderstand each other, or be unable to communicate effectively. For thousands of years humans have wanted to naturally speak with each other, and finally this dream will be a reality.
Soul mates
What could be greater than to replicate nature's greatest feat of engineering? The possibility that, within the next 30 years, humanity will engineer the hardware and software required to build a computer that shows signs of consciousness. It is an idea explored extensively by science fiction, but given that the current scientific understanding of self-awareness resides in the actions of chemicals and neurons, should the development of a conscious computer be anything other than inevitable? This birth of a new, nascent, alien intelligence in the universe would have potentially the single most momentous impact on civilisation imaginable.

The runner-up, with 2654 votes (about 30%), is...

*drum roll*

Soul mates, aka building conscious machines 
(for a dialogue concerning virtual brains, click here)

And the winner (who wins a trip to Svalbard, in the Arctic Circle, north of the Norwegian mainland, to visit Statoil's giant Troll gas platform where he or she will descend to the bottom of the North Sea), with 3097 votes (about 35%), is...

*drum roll*

Nanorobots fight the medical battles of the future. 
(For some recent work on cancer-fighting nanotechnology, click here for a tag-team approach, and here for a magnetic one.)

Deserved winner?