NetParty -- According to Forbes, Netparty functions as the entry point for a network of parties held in 17 U.S. cities, aimed at professionals in their 20s and 30s. The events, held at stylish clubs, are designed to combine business networking with social fun.

Networking for Professionals -- an online networking group designed for professionals from numerous occupations, where you can build your business, improve your client base, and/or advance your career.

PowerMingle.com -- Based in London, Powermingle Ltd, provides services for effective, interpersonal, business networking at events and in organizations and associations.

Real Contacts -- a worldwide online employment service for permanent or temporary jobs that brings employers and job-seekers together through their extended network of contacts.

Twitter- a web site and service that lets users send short text messages up to 140 characters in length from their cellphones to a group of people. 

XING -- committed to powering relationships based on trust for all professional people.

Ziggs -- offers a search platform for professionals for finding people in business online.

ZoomInfo.com -- business-information search engine, with profiles on more than 45 million people and 5 million companies. ZoomInfo delivers a single site for quick and easy access to in-depth information on industries, companies, people, products, services and jobs. Job-seekers can post/edit your free profile, which can include your professional career details, bio, education, affiliations, contact information and Web references.

Additional social networking sites:

del.icio.us - place to share your personal bookmarks with an entire community of other people -- and where you can see what sites other people are bookmarking.  

Delphi Forums -- one of the leading networks of member-managed online communities. Delphi's services enable individuals to build, manage and grow their own online communities.

Digg.com -- is a social news sharing for people to discover and share content from anywhere on the web.

Friendster -- Friendster is an online community that connects people through networks of friends for dating, making new friends, and helping your friends meet new people.

hi5 -- an online networking site for meeting new people, connecting with friends, and sharing ideas.

iMantri -- an online peer-to-peer community for seeking and offering mentoring and coaching. The site facilitates connections between mentors and mentees and also provides a framework and tools for fostering mentoring relationships online.

Meetup -- helps people get together with a group of neighbors who share a common interest (46,315 groups and 4.7 million are part of Meetup).

MySpace.com -- is a social networking site that consists of worldwide community of users who share information, photos, videos, music, and more. You could decide whether to create a personal MySpace profile or develop one for your business.

Squidoo.com -- a social bookmarking site started by marketing guru Seth Godin, this site gives users a chance to showcase expertise in one or more areas by creating knowledge pages, called lenses… and the person creating each lens is, of course, called a lensmaster. Using this site gives you a chance to showcase your knowledge and link and promote your site.