There are no small ads, just small ad platforms. That may be the theory behind a recent move by the folks at Twitter, who have begun testing small text ads beneath Tweets -- the short-form blurbs the site's members blurt out whenever the mood strikes them.

So far, the text ads are only tests, but Twitter could soon attach ads informing users -- many of whom are considered early adopters -- of new products and services.

In a recent Guardian story, Twitter was also reported to be working on branded channels where companies can connect with users without interrupting personal communications. According to Ev Williams of Twitter, the possibility of branded channels presents an alternative to advertising inside personal communications.

Twitter, which is less than two years old, has attracted a devoted base of about 350,000 users.