Tumblr blogging friends: I feel like I can never interact with your blogs because of the non-comments. But then, perhaps you prefer it that way.
If you have a Tumblr account, you can leave a reply on the posts of the people you follow*. It's not as interactive as comments, but it's something.
*I think it takes two weeks from the point you start following someone for you to be able to leave a reply. And you can only reply to the people who have allowed for replies in their settings.