The Seattle Times: Business & Technology: Skype's online calling rings through industry: "Skype is adding 130,000 registered users a day — in the process creating its own vocabulary, as in "skype me" — all without spending a cent on advertising.
Skype gets revenue in two ways. The first, SkypeOut, lets users place calls to regular phones for about 1.7 euro cents a minute. Callers buy prepaid calling cards for 10 euros ($12), which provide about 600 minutes.
The second source of revenue, SkypeIn, provides users with a phone number so they can receive calls from regular phones. A customer in London can get a San Francisco number that lets friends and family in California call him or her at local rates. The service costs 30 euros a year.
Zennstrom says about 5 percent of Skype users pay for one plan or the other.
Zennstrom estimates that as many as 30 percent of skypers are business clients such as Kern and Vollenweider."
Check the full article for details on how AOL plans to challenge Skype.