I'm always so surprised when I meet someone, we have a great connection, they tell me they'll be in touch, and then wham -- nothing. It surprises me because the hardest part of networking is actually starting. It's the getting to the event, or organizing the get together. The rest is quite easy.
I've had so many situations where I've spent a flight next to someone and they'll be telling me about a problem they're experiencing, or about someone they need to meet in a certain industry, and I'll offer to help them out. I give them my card and tell them to be in touch with me.
Same goes for networking events. You get along really well with someone and you know that you can help them out heaps (and they know it too) but then they never take it a step further. Business cards and smiles are exchanged, but it's a wasted opportunity as they never do anything about it.
The most important part of networking is to follow up - to take the conversation to the next level -- to build the relationship. I've found a good way to do this is to diarize some time after networking events so that when you get back to your desk, you'll be reminded to follow up.
Emma Isaacs is the CEO of Business Chicks and writes a regular blog at www.emmaisaacs.com