Web design company looking for individuals to call companies to get leads. What's the best way to do this? We've tried craigslist already.?

There are lots of companies and services out there.

You might find independent contractors on places like Fiverr and Odesk.

There are also companies everywhere that supply such workers.

There are also outbound call centers that do it.

You are obviously not offering enough pay and benefits. Give me $15.00 an hour, to start, a $.50 an hour bump at 3 months and 6 months with a 4% yearly cost of living increase, after that, and full employer paid health insurance and a 401K and pay my Verizon bill. I will do it from home. I've done cold calls for minimum wage against commission already, and was good at it. Screw that! I also know some other experienced people I can get you, for a decent bird dog fee.

Try LinkedIn instead. You can search for people with sales or "business development" experience in digital marketing or SEO. That would be the easiest place to start IMO.