Liz Castro's excellent blog, Pigs, Gourds and Wikis, covers the reality of gatekeepers in "We're not the media if we depend on Google (or Amazon)." Yep.
free PDF download (hat tip to Kevin Kelly's Cool Tools blog). Though it's severely outdated and aimed at computer and craft entrepreneurs, it provides some wise advice for writers of today. Plus it's a hilarious read chock full of quotables, e.g.:
The worst information sink, of course, is television. It puts you in a passive, comatose state. It spoon feeds you drivel. It is in total control of what it gives you. It makes you expect the instant and certain solution to everything in precisely half an hour. It lacks subtlety, degree, option. It averages you in with the Epsilon minuses. Worst of all, it rents your bod out to the highest bidder, something that the civil war purportedly decided was a no-no.