Will the pendulum swing back from ads to subs again?

Dan Farber: "If you like Twitter so much, how about paying $5 a month"

2 years ago, I wrote: "It's hard to serve the people best when the money's coming from somewhere else. When The First Online Ad Bubble burst, everyone was in awe of AOL's subscription business... Calacanis [wrote then] in 2001 about how the future is consumer subscriptions and people paying for stuff." [Calacanis is now in one of the only viable online ad businesses (where the ads make the service better): Search (Mahalo).]

More entrepreneurs should have the guts to charge for their great product. Examples of successful web service subscription businesses include 37signals, TheLadders, Meetup, and I'm sure there are others.