In 2007, Dell launched their IdeaStorm site. It was the first example I had seen of a website where users can go to vote on features. From their FAQ:
The name is a take-off on the word "brainstorm" and it is our way of building an online community that brings all of us closer to the creative side of technology by allowing you to share ideas and collaborate with one another. The goal is for you, the customer, to tell Dell what new products or services you’d like to see Dell develop. We hope this site fosters a candid and robust conversation about your ideas.
As of Dec 2009, some of the most popular requests are:
Shortly afterwards, we launched Bullhorn Brainstorm, which is based on the open-source pligg project. Leveraging pligg allowed us to deploy a working site after just three days of evaluation and coding. Six months later, we spent some more time doing a visual refresh.
The results have been amazing. In a little less than a year, we have had 1,750 feature requests, by 700 distinct users. There are also 20,000 votes from 2,450 distinct users. This is for a product with 14,000 users. What's more, the voting is not tailing off over time:
For us, the site has been a huge win. It allows us to discover good ideas, and justify not spending time on unpopular ones. To date, we've implemented about 50 of the requests.