Crazy Egg's company blog offers marketing advice on website conversion, A/B testing, SEO, and web design.
HN commenters link it for explanations of concepts like conversion funnels; they give no strong opinion on its quality.
1. Tweet surveys out to hashtags.
2. Go (literally, physically) to places where your customers hang out. (Starbucks.)
3. Post in Facebook groups you think your customers would Like.
4. Post in LinkedIn groups you think professionals who'd buy your tool would participate in.
5. etc.
There are so many examples out there. Just brew some coffee, Google "how to get customer feedback", and take notes for an hour. You'll be set for at least a week of experiments.
* http://blog.kissmetrics.com/best-ways-to-get-feedback/
* https://www.helpscout.net/blog/customer-feedback/
* http://www.desk.com/blog/customer-feedback/
* http://blog.crazyegg.com/2013/09/17/customer-reviews-that-convert/
* http://insideintercom.io/3-rules-for-customer-feedback/
Tightening the funnel means that potential customers are less likely to go all the way through to signing up and becoming a regular customer.
https://blog.crazyegg.com/2014/03/03/website-conversion-funnel/