- Xing https://www.xing.com/en
It is mainly oriented on the European audience. Comparing it to LinkedIn, one main difference for XING is that in each bigger geographic center, XING network has its representative, who periodically organizes meeting and conferences, so each user might feel like he/she is a part of some kindof closed group/ business club.
2. Branch Out
This is the one of the biggest apps on FB. It has started its activity from 2010.The key feature is that you can actually add to your BrachOut profile other users, who are not on your FB friends list.
This is a network dedicated to entrepreneurs and mentors, basically it is oriented on finding potential clients, connects with investors and finding funding.
Another network where you can get offer from top tech companies and startups
5. Upspring- http://www.upspring.com/aboutus
Nice markerplace for you to communicate with other businesses. You can register and add your profile as a proffesionl or as a business.