Mailchimp is one of the better options (I use it with all of my clients). They've created some great getting started documentation: http://kb.mailchimp.com/.
There are some sites that generate decent Amazon Associates revenue without millions of visitors — it's a question of whether one of the main interactions users expect to make with your site is buying something from Amazon. Considering what you're building, it's worth at least experimenting with. Other booksellers (like Powells) have their own affiliate programs too.
For me, one of the strategies that made a lot of difference was checking what tasks I could do where, since there was plenty of work I needed to do away from the computer. The context that a task takes place in matters a surprising amount.
Beyond that, though, I'm very intrigued by the idea of the tool adapting to work habits. Looks interesting!
