Scott, I've been curious: why don't you have a direct donation option on the site?  I understand you're looking for support in the form of books sold, but it seems like it couldn't hurt to have the paypal button or whatever.  Leo Laporte of Twit.tv has buttons up where you can do a one-time contribution, or recurring monthly contributions of $2, $5, or $10.  There's so much great content you've already put out that won't make its way into print for a while if everything goes according to plan--seems like it would make sense to have a way for people to compensate you for it directly.

Don't know if this is too intrusive a question--just wondering if you had some specific reason for not doing it.