My #1 favorite thing to do at Google was hosting authors (search "bob's author talks" on YouTube, although it didn't work for me just now). The thing about those talks is: they were almost 100% authors with a publisher behind them. The publisher would pay for their book tours. A self-published author might manage to give a talk at Google or the 92nd Street Y in NYC, but it would be tough.

They can also get your book reviewed in the few publications that still review books, and they can send their catalogs to bookstores. But yeah, they take more of the money than a self-publishing arrangement will take.