More great comments are coming in (thankyou). S Miller offered a comment on yesterday's post about the etiquette of including her signature block in a "reply-all" email.
Your signature block (a block of text with your contact info, links, etc.) is a very simple and very effective marketing tool. The great thing about them is that they are fairly unobtrusive and most people are very accepting of them in almost any email they receive (of course, if you're sending something out to family and friends you should probably preface your signature block with a more personal closing).
You should be able to set up your signature in your email software so that it is automatically attached to each message you send out (one of the reasons they're so accepted).
Things to include in your signature block
Phone number, cell, fax, email address, mailing address, titles of your books or syndicated columns or blogs, plus a link to your website/blog.
4700 E. Galbraith Rd
Cincinnati, OH 45227