I enjoyed following this person's trip:
http://imjustwalkin.com/He setup a blog prior to leaving and made many posts every day. I think they also setup some web script that let him ping his location to his website whenever he wanted. It was very easy to track him.
Why would you need Quora? Instagram could be neat.
Depends what your reasons for walking across the country are. If it is to escape the pressures of every day business life, then I'm not sure you'd want all that much technology.