How do people use LinkedIn and/or similar networking sites?

What benefits do you see in Linked in? How do you use it? For me the benefits so far are:

1) It provides a way to get in touch with people I knew well 15 years ago but have lost touch with.

2) Interesting to see how their careers have developed or not

3) Useful to know that I am not the only one to have had 5 jobs in 10 years

4) Picked up some good ideas from other people's CVs

5) Can find a friend of a friend at pretty much any company.

Is there anything else?

All of the above and:

1. Knowledge share - the groups offer a forum to share knowledge and experience

2. Bus Dev - it's a way to identify key stakeholders and a non-confrontational way to approach a potential client target

3. Job hunt - I got my current contract and the perm job I start next month (as well as two other jobs I was in process with) via Linkedin direct approaches to and from connections in my network.

I see the benefits as:

1) Stalking ex-colleagues

2) Being nosey

3) Researching people you want to 'dig dirt' on

4) Spotting job-hobbers

5) Spamming people

6) Boasting about how many people I know

7) Stroking my ego and thinking that everyone on the net wants to know about me

8) Looking for people I know who have accidentally put a little too much info on their profile

9) Providing recruitment consultants with a searchable directory of people to call

10) Having to maintain my LinkedIn profile as well as about 1000 others (Pipl, Bebo, Facebook, Xing and so on).

I got my end away with some bird I hadn't seen since college.

Got well and truly Linked In to her