Lurkers are people who read, but do not participate in online communities, such as forums, discussion groups, blogs, and wikis. Lurkers hang out but rarly add an content or value.
I read somewhere about the one per cent rule-of-thumb. It suggests about one per cent of people contribute new content to an online community, another nine percent comment, and the rest lurk.
However, this may not be a passive role because content read on forums may spark interaction elsewhere.
In fact, it's amazing what you can learn lurking around a site where your target audiance hangs out. For example you can learn the language they talk. Industry jargon and the many ways an industry sells and markets themselves.
Lurking can be used as attentive listening before speaking; potentially the solution to all Internet faux pas.
You can also learn the latest new, changes and problems effecting that industry or target group.
It's smart market planning to lurk on targeted Websites, Discovering new way to go after your ideal future client.
Budget: 4-5 hours a week, $125 - $300