Jackie Huba posts a recap of their recent book tour to promote Citizen Marketers. She lists a number of stats, two of which are shown below:

- Number of books sold: 7,445
- Blog subscriber increase from 15,735 to 47,798 during tour, via Feedburner. (The jump in subscribers on 2/18 is due to Feedburner adding Google Reader subscribers.The hiccups in May are due to a Google problem in reporting subscriber counts to Feedburner.)

Jackie notes that the increase might be related to the Google Reader. Even if the under-reporting at first was 100%, i.e. instead of a baseline of 15K it was 30K, that's still an 18K increase in subscribers. On the low end Jackie and Ben now have 18K new readers/potential customers. On the high end it's 32,000.

While the primary goal of a book tour is to sell books, I think the increase in RSS subscribers is a more important result.