If you own an iPhone/iPod Touch and happen to read books on it via the free Stanza (iTunes link) app you could enrich Barnes&Nobles by buying books via the app.

So what did Amazon do? They bought Lexcycle, the developers of Stanza. I would expect that any time now, Amazon will come out with a new version of Kindle for the iPhone that will, in effect, be a rebranded version of Stanza. Some things do get through the cracks, however. Amazon now owns Lexcycle/Stanza, Stanza sells current books through Fictionwise. Fictionwise is owned by Barnes & Noble. I didn’t believe it either, but it’s true. Amazon is making money for B&N, at least for now

Via TUAW.