Social networking sites -- using input from readers in building and rating content -- are merging with multimedia to produce a flock of new companies. History says few will last, but sorting out those that will is a fascinating exercise. So is figuring out just where small, powerful digital tools are taking us.

Evoca, for example, is a Savannah-based company with a jazzy idea that's gaining traction.

The company specializes in online audio, offering user-friendly ways to post sound clips on Web sites and set up podcasts, those downloadable audio programs that let you take your content with you on a portable music player. The concept is that until a new trend becomes easy to use, it will remain in select hands. Simplify it, and a mass audience might just appear.

I'm seeing more and more Web logs that use podcasts, a nice way to manage content for those who are on the go but want to keep up with their favorite sites. But posting audio snippets doesn't have to be a function of Web log publishers alone. Evoca (www.evoca.com) lets you cut and paste HTML code to embed audio into any kind of Web page. You might want to describe a product you're selling on eBay via a sound file, or use the medium to play snippets of music you've created.

To take the headaches out of posting sound files, Evoca is telephone-friendly. You can record your thoughts by telephone call, after which they will make their appearance in a holding area at the site. Your words go public when and if you choose to enable them. Telephone options like these (Evoca lets you record Skype calls with a $5 a month premium account) free you from microphones and let you post audio observations from anywhere you have a cell phone signal.

Podcasts can be enabled with RSS feeds so users are alerted when new content appears, making Evoca a useful audio blogging tool. The community aspect is reinforced by tagging, in which users add key words to make their recordings easier to find. Searching gets more interesting when you use Evoca's speech-recognition tools, which provide full search capabilities for sound files, a technology that will grow in importance as online audio takes off.

But what online audio services lack are the editing capabilities that would allow users to apply tweaks and finishing touches to their podcasts. There are good PC-based applications for doing such things (I prefer an open-source program called Audacity), but where they would really come in handy online is in travel situations, when updating content on the road would require only a Web connection.

Evoca still has a lot of rough edges: Even its Web site could use some work. In addition, the amount of content posted by users at the site is minimal, in contrast to rival Odeo's claim of one million audio files (www.odeo.com). But watch how this sector develops, and if you get interested, take a look at what ZapZap is doing with multimedia content management.

The site (www.zapzap.com) is designed to be an aggregator of video and audio feeds. But treating it as a simple directory of multimedia would be a mistake, because ZapZap provides playlist capabilities that can add the podcasts, and videos users download most into a playlist. That results in a community-defined popularity ranking, letting you see or hear which content is getting the most play, and feeding it into your audio player. Its automated features make ZapZap an interesting contribution to online multimedia.

Years ago, I had a friend who, while traveling in the Sudan, worked as a stringer for Time magazine, the idea being that if something happened in that country, he would report in to allow the editors to decide how to cover it.

Today, we're creating stringers out of anyone with a video or audio recorder who wants to contribute. Think of the video footage coming out of Lebanon on YouTube.

Sure, this technology is in its infancy, and much of today's content is sophomoric, but the longer-term picture is fascinating. As tools improve and people record what they see and hear, a multimedia-enabled public journalism emerges on the Internet. This is surely a plus for the process of news gathering, because it helps to provide the raw content upon which ideas are based and decisions made.

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