In addition to interacting with your site visitors through comments on your blog posts and pages, there are a handful of other simple things you can implement on your website that will engage your readership:

• Polls. Polls are a way for your readership to feel involved in your story – they allow a reader’s voice to be heard, however anonymously, but are also a great tool for finding out more of what your readership wants from your site. Rather than wonder if your readership wants more content about subject “x” – either mine your data to find out whether it’s successful, or just ask them through a poll. There are a number of free, simple, poll generators, but PollDaddy is a great place to start.
• Photos. Just like you can use something like an Instagram plugin to place your own Instagram photos on your site, you can invite other people to tag their photos with a specific hashtag and then use that hashtag to determine what shows on your site. This is a great way to invite audience participation whether it’s around creating something, going somewhere, or any number of common experiences. If you’re concerned that people might take advantage, then create something like a Flickr group where you approve membership to add photos to the group, then base your feed on the group’s content. Photos are a great way to feel connected to an audience, and videos as well!
• Competitions. Ask your readers to come up with the best way to do something, then give an award for the best answer/submission. It doesn’t have to be a big giveaway – people love to get stuff for free, no matter how small, and if a competition brings you a large audience, it’s well worth the investment. Your giveaway could be some free time with you if you’re a consultant, or a copy of your book if you’re an author, or a coffee mug with your logo on it no matter who you are.