Contacting me by email.
Visitors who message me through the Contact page supply their
email address (though it's possible to use a fake one).
Those messages go straight to my own email account; I don't
maintain a database of names or addresses of visitors who
contact me. If you send me a particularly ridiculous
message I might publish it to make fun of you.
Drawings & Contests. About a decade ago I ran some drawings and contests, and might do so again in the future. Generally for these events the only personally-identifiable information required for entry is an email address so I can contact you if you win. If the prize is something I need to postal-mail to you, then at that time I'll also need a name and mailing address. Winners are identified publicly by first name and last initial, or by full name if you agree, and by city if you agree.
Email newsletters. I used to send out newsletters by email, and then publish them on the site. I no longer do so, but might do so again in the future. Users submitted their email addresses via a web form in order to sign up for the newsletter, and could unsubscribe easily at any time. I still have the old list of subscribers. If I ever sell the site, I will not sell the subscriber list. The only thing I can think that would cause me to divulge the subscriber list is a court order.
Log data. Like just about every website on the Internet, my server records log data about visits, with a line listing things like the IP address of the visitor, what file from my server was requested, the date and time of the request, and the browser the visitor is using. This lets me see things like how many people visit the site and what pages are the most popular. In general, I can't really identify any individual user from this information. If you send me an email message about a certain article I could theoretically look through the logfiles and see if you were the only one who looked at that page in the last couple of hours, but then what could I possibly do with the fact that I saw what browser you used? I don't think there's a black market in Mexico for information about what browser someone used to access a website.
Geolocation. I use geolocation software to figure out what country you're browsing from, to show you ads revelant to your country. I don't save this information and I can't identify you with it anyway.
August 2017: Clean up wording about email.
July 2017: First post.