I know this isn't new, but I just recently paid some attention to the LinkedIn social networking site. I found it to be a very interesting and creative spin on using the social networking power found on the Internet to connect co-workers and former co-workers. Not only that, it contains features to help each other advance themselves professionally. I have only been a member for about a week, but my first impression of this web site is very positive.
One immediate frustration I have experienced was when I first began searching for co-workers from a previous employer. Being a programmer and having created my own search services, I wrongly assumed that I could search using all lowercase letters. While the search did indeed work, the site saved this search using the lowercase letters. If there is a way to edit the job title and employer name, it is not easily found. Now, I look incredibly unprofessional on a professional networking web site. Ugh!!!
In case you are interesting, my LinkedIn profile is here.