Its means to create valuable content for your market, and then share the content through links. From tweeting the link, to posting on a social network, to posting to web forums, to posting as a blog comment. But always stay in context. Don't post a link to post a link.
This works very well and has a long term impact. Plus it improves your search rankings.
Link building can often be bad like you imply. I think the right way to do it is to find the right places to share content with the right people so it spreads organically. I am not sure I would agree that creating new accounts on lots of platforms and creating links is a good or sustainable practice these days...