Crazy stuff happening with Google Adwords: they have added the ability to do opt-in emails inside of the adwords advertisement. This is some pretty cool stuff, and really expands the ability to immediately interact with users and I honestly think provides a whole new opportunity for affiliates.
Google has really tried to keep affiliates from promoting offers, but this way affiliates can drive targeted users to email lists immediately, in theory auto-respond them and then build lists. I’m not sure of the details, as its right now only available for GMAIL users, but it seems like it could be a lot more.