Oh, mate, the amount of times people try to pitch you something is absurd. I used to try to reply to them but then they smell a sale and won't leave you alone. The best ones are the ones that get froggy when you ignore them and ask why you haven't replied.
I've been approached for jobs a few times and although only one ever materialised it was more to do with me not fancying it, so I'd say linkedin definitely has a function. I find it useful for connecting with people you want to maintain distance with but have some kind of link. I like to be...