I can't stress enough how many times I read that 1 of the main benefits to getting an MBA is establishing a network with current and future leaders (& professionals) (business, public or otherwise). As things begin to wind down at my current position, I've been concentrating on using the tool Linked In .
I want to suggest to everyone as you quit your old job that you use this tool. Linked in is great because its specific for professional networking, not teenage flirting (See Here). I'm looking forward to having this because it can serve as a directory for me as my colleagues and I change contact information over the years. I also plan on calling upon many of the people in my network for help and hopefully I'll be able to help them as well.
Your network is great and powerful. It can help you find people to sell to. It can help you find professionals you need services of. It can help you find potential employers or employees. It can help you gather information.
Use this tool. There are so many books that talk about the power of networks and I'm not going to list them all, but " Love is the Killer App" is one that I have really enjoyed.