I've never actually found a job through LinkedIn, but I appreciate that it COULD be a good way to do so. It's got the potential. I think it just needs a few product changes and a whole lot more credibility with respect to customer privacy, and it could be a really great platform.
Unlike most of HN, I actually appreciate recruiters reaching out and I try to get back to each of them, if only to just understand what's out there, what possibilities I may be overlooking.
I use it as a way to get free interview practice. Any recruiter contact I am interested in I will reach out to and entertain the interview process for. Whether I am looking for not I have no problem getting free practice and if I find a team/company I like I might just change jobs.
I use it to chuckle over emails suggesting I endorse people I don't know for skills I'm not certain they have. I also enjoy when people who don't know me endorse me for skills they can't possibly know I have, and may not even possess. It's a cute game.