Looking for a few new ideas. Tactics we use already:
+ Create a "best of" page
+ Link to old posts in new posts
+ Share old posts on social
+ Create a new related image to share with the post
What else should we be thinking about?
If you have a self-hosted Wordpress blog, there is a great free plugin called "Tweet Old Posts" which will promote older posts on a schedule you set.
It works really well and is simple to setup.
Another idea is to repurpose your old content into fresh, new content. If you've got a series of related, older posts, consider putting those into some sort of downloadable pdf (in exchange for email ) that your readers can take with them and then link to the old posts in that PDF.
If you're creating a 'how-to' guide and using older posts as some of the content, make sure to link directly to those posts in the PDF. Head over to http://blog.hubspot.com/ for awesome examples of this in production.
Assuming you're running WordPress, you should explore the plugin called Insights from Vladimir Prelovac ( http://www.prelovac.com/vladimir/wordpress-plugins/insights ) to help you connect with older content and media, as well as SEO Smart Links ( http://www.prelovac.com/vladimir/wordpress-plugins/seo-smart-links ) to help you automatically interlink older posts.
A third option is to fire up Adwords and build a campaign around your old posts. If you're doing this, then ensure that you're funneling those paid-for clicks from Google > Old Posts > call to action to New Post / Subscriber. Capturing new visitors and showing them your great archived posts, then pushing them to new ones has been quite effective for our customers and encouraging engagement.
You can also make:
updates to the old posts
write a follow-up posts to the old ones
repurpose your content: use the blog posts to write an ebook, make a webinar, etc.
make different lists of your posts in a post
make a youtube video on the same topic and link to the blog post in the description
Consider writing the "Best of" page, but don't put it on your site. Instead, use it as a guest blog post on another site. The links will go to you and it's great content for the other blog.
Thanks, everyone! These are all great ideas!