The following is a (non-comprehensive) list of reasons to say that this tech is part of the Elastic Technologies family. Please, be aware that it can be changed anytime, adding new reasons found as we continue making intensive use of it.
Best API/Webservice player out there
Building lightweight API's is something where node.js really shines make it a great choice for wrapping databases or web services.
Efficiency handling heavy-requests apps
Think about pages as Gmail. Node.js has the ability to process many requests per seconds with low response times, as well as sharing things like validation code between the client and server, make it a great choice for modern web applications that do lots of processing on the client.
No need to reinvent the wheel
Node has the ability to spawn thousands of child processes and gathering together their outputs efficiently, which make it ideal for those seeking to leverage existing software.
Soft real-time applications
Think about stuff like twitter, chat software, sports bets or interfaces to instant messaging networks.
At this point the node.js community is growing at an insane pace, attracting some of the smartest developers in the industry. This also means that the node ecosystem is growing every day, and it's also easy to get free and commercial support from various sources. Even, it’s named “the biggest shift in enterprise application development in more than a decade” by Forrester.