I definitely believe in the power of offline networking. I am a member of our local Chamber of Commerce where I volunteer as an Ambassador--promoting the Chamber as well as attending all of the new business ribbon cutting events, etc. It's a great way to meet new people and talk to the new business owners about my VA business and get my "face" out there. From that membership, I got one client that I did some project work for.
What I have received the most benefit from is local networking groups. I joined two groups and already have two current clients and seven potential clients (wish me luck).

The value to me from the networking groups is that you help each other--they help refer you to their contacts and you do the same for them. People seem to be very interested in the VA business but just need to be educated about the details.
The most recent event I did was to be the "guest speaker" at a local civic club. Don't get too excited--#1 I HATE to speak in front of people and #2 there were only 9 people there. HOWEVER, one of the ladies present was the manager at a local credit union and they will be needing additional help towards the end of the year. She is VERY interested in what I do. That could be potential client #8.
So, bottom line to me is that offline networking is VERY important! I find that online marketing of my business is much harder and you also don't get the benefit of meeting your clients in person. BTW, I just started my VA business in March and have only been "working" it part-time.
I'd love to hear how other VA's feel about offline marketing!