Carola Heine sent me an invitation to LinkedIn.com. LinkedIn is a business networking platform where people build networks of trusted contacts, and are supposed to discover inside connections to recommended job candidates, industry experts and business partners. I joined LinkedIn (here is my profile) and had a quick look around: Building up personal networks and offering or finding jobs seem to be core functions, with little more to go with that. Feel free to add me to your connection list if you're a user of LinkedIn. If you're not, don't bother.

Generally, I like the Open Business Club (OpenBC) much better. It's an internationalized platform for contact management and networking, based in Hamburg, Germany.
OpenBC has many additional functions like private messaging, discussion forums on many profession-related topics, an event manager for appointments, lots and lots of contact details, and much more. I already have a couple of contacts there, so feel free to have a look at my OpenBC contact page, and join my personal network.

Carola wrote that she doesn't expect to be using OpenBC much in the near future, but I reckon that is because she already built up a lot of professional networks and contacts through traditional, non-social-networking-platform-based means. ;-)