If you want to turn anonymous visitors into identifiable leads, a blog subscription is a great place to start. Exchanging an email address for weekly content updates is a decent trade; and you can sweeten the deal by offering a free gift as an added incentive.
Whilst you may be reluctant to part with a valuable eBook for something as lowly as a name and email address, creating a blog mailing list is a hugely powerful tool for lead nurturing. The more valuable (and thus desirable) your offer, the more engaged, grateful and receptive your new contacts will be.