Conferences are great - we've had a lot of success nailing clients in tech/industry conferences. Of course, you should be selective on the ones you choose to attend (avoid the high price/high BS ration ones).
Also, cold e-mails can work surprisingly well if you can lead with a warm-ish intro. Follow them on twitter, read their blog posts, quote their CEO, whatever.. Just something so that the recipient appreciates that this is not a generic email and understands that you've put effort into it.
Very good suggestion. It takes effort to maintain personal, specific and valuable communications ... but it's worth it. The bland, generic stuff really taints the brand.
In my experience conferences are rarely attended by the real decision makers. So you'll need to accept that the people you network with are possibly several steps removed to the ones you are really trying to reach. Which means that you need to tailor your communications to suit at each of the levels so that the people along the chain of command gain from your interaction with them.
Also, cold e-mails can work surprisingly well if you can lead with a warm-ish intro. Follow them on twitter, read their blog posts, quote their CEO, whatever.. Just something so that the recipient appreciates that this is not a generic email and understands that you've put effort into it.