Eventually, to get any benefit from your network of contacts you are going to have to organize them I've decided to try out Plaxo again, as they have made a number of improvements, including streams, google maps and other bits and bobs since I last looked at it properly.
For example I am currently in the process of sorting through all my connections on mybloglog and Ning, checking what they do - how they can be useful to my business or maybe who I'd not mind meeting for a business chat to learn more about what they do, possible JV's etc.
most of this needs to be done manually - the benefit of that is if they are already on Plaxo a mini resume/mini profile comes up with a map - in short is a way to get to know who you are connected with as individuals - and real social networking / business networking is about getting to know what people do, to build up a mental rolodex of who can help who - and who can help you / who you can help etc.
One bonus is you can also sync your plaxo account with your facebook account - so any friends already using Plaxo will show up as people you can connect with.
Using plaxo is a way to get to know people rather than the mass broadcasts which are largely ineffective on most networks (apart from twitter) as people switch of their e-mails/get fed up with it - example I have over 5000 e-mails in my Ning account, I will plow through them eventually but most are send by people that prevent return e-mails - if you are going to broadcast - it has to be a two way willingness to connect in my opinion or it becomes spam.
Anyway for people that want to connect you are more than welcome :-)
Plaxo is free - there is a premium version but for now the freebie is helping me enough to get a better sense of who is out there and what they do.