More people using Google's other products.
Over the past year, while I've had my Android handset, I've become a massive user of Google stuff. Google Docs, Maps, Picasa and Mail integrate pretty badly into it, but better than anything else, and so that's what I use from my phone. Since everything's already there, I do the same from a real PC.
I've tried a couple of times, and only really half-arsedly, to change this, but it's not that easy. The bundled non-gmail mail client is atrocious, there's no good Flickr clients and I've not found any real alternative to crippled-google-docs for my G1.
Google might get no money from me using the phone, but they get loads more ad views than they otherwise would when I carry on using what's on my phone on a proper screen.