It’s no secret that I am not a fan of anything that require users to “check in” to various locations. Why? Two reasons:

1) It tells people where you’re not - at home. If anyone is looking to rob your house, this would be the time to do it.

2) It tells people where you are - and if anyone is looking to cause problems for you personally, they know how to find you.

However, there are a few times when I think something like Foursquare might be useful. For example, if you’re doing a book signing, you could “check in” and give fans a reminder about when and where the signing is. Or you could check in at a coffee shop nearby after the event, and give loyal fans a chance to come out for a bit more of an intimate meet-the-author event.

You could run a contest at an author event - everyone who checks in to Foursquare at your event can win a signed set of books, or free swag, etc.

You could also use Foursquare if you’re attending conferences, giving readings, or appearing publicly for any reason. If you’re appearing somewhere publicly anyway, people will already be able to find out where you’ll be at that time, and so there’s no additional safety risk. However, you may want to make sure you have a good home alarm and insurance policy in place!