Are you a small-business owner or independent contractor on the lookout for an easy-to-use webconferencing tool? Well, your search may be over, now that a San Francisco-based company called SlideShare has unveiled Zipcast.With more than 45 million unique Web visitors each month, SlideShare allows users to upload and view slide presentations for free. The idea is certainly catching on: Company execs say that tens of thousands of slide shows are uploaded every day and the average visitor spends 8 minutes at the site viewing 20 slides. As for the content, it's as diverse as the user base. Want an explanation of the U.S. healthcare system? Interested in the "science of speed"? Need some tips on using social media? You'll find presentations on those topics, and a whole lot more, at Slideshare.com.

Now SlideShare has made its presentations interactive, with a webconferencing tool called Zipcast. "We've polled our users and found out that webconferencing is a popular tool for them," says Rashmi Sinha, CEO and co-founder of SlideShare. "But many of the applications out there are stuck in the 1990s. They're not intuitive, and they're difficult to use."

But not Zipcast, Sinha says. Here are some of the features that SlideShare is touting:

Easy to use and affordable. Webconference participants need only one thing: an up-to-date browser. There's no software to download. Each SlideShare member gets a URL--a "virtual" meeting room, if you will. To host a webconference, the user shares her meeting room link with participants and uploads the presentation she'd like to use; otherwise, she can use any of the public presentations available at the SlideShare web site. The technology scales, so there's no limit to the number of people who can join a meeting, and video streaming is fast. New SlideShare users can sign up by filling out a brief online form, or through Facebook Connect. Zipcasts are free, unless you want password-protected access to your meetings. Then you can opt for SlideShare Pro, which starts at $19 a month.

Integrated with social networks. During a Zipcast, participants can talk to each other via a "chat area" in the bottom-right section of their browser windows. Those chats can be pushed out to Facebook or Twitter, drawing new participants to the meeting. The SlideShare home page displays an "activity feed"--a log of current public meetings--so existing users can jump into a webcast whenever they want. Meeting hosts can use a social media site to invite participants as well.

Free teleconferencing and streaming video. Zipcasts feature one-way audio, group chat, and one-to-many streaming video. But through a partnership with FreeConference.com, SlideShare also offers teleconferencing options, such as two-way audio.

Sinha foresees two use cases for Zipcasts: 1) basic web meetings with slides, audio, and just a few participants and 2) webinars, or large public events. "Given the social media connectivity that's integrated with our Zipcasts, webinar participation could be viral," Sinha says. "You can start an event with 50 people, syndicate the chats on Facebook, and end up with 500 participants before you know it."

According to analyst firms and industry experts, webconferencing isn't just a passing fad. Gartner expects webconferencing software to be a standard application, alongside e-mail and calendaring, for 75% of corporate users this year. And Frost & Sullivan estimates that the webconferencing market will grow to $4 billion by 2014.