NationBuilder sites have a default universal sidebar. It's very flexible and has all kinds of customization options based on whether a user is logged in or not. It's also really easy to embed a BlogTalkRadio player in the sidebar so you can share your shows from the popular freemium podcasting platform.
A while back, I moved my personal website from WordPress.com to WordPress.org primarily so I could easily embed the BlogTalkRadio player for my show, Gov 2.0 Radio. NationBuilder's standard sites support embedding of the BTR players in page templates, and the default player is also a perfect fit for the sidebar.
To edit the sidebar and embed your player, you'll need a custom theme. In the example above, you're seeing a clone of NationBuilder's official "Paper" theme. Then you go into the theme templates and edit the file called "_columns_2.html." Grab the BlogTalkRadio embed code for your show and paste it into the template file right after "<div class="right_column">." For my player, I edited the BTR default code just a bit to change the text and link to the show page on BlogTalkRadio.com, moved that text and link above the player, and added a link to the Gov 2.0 Radio archives on iTunes below the player.
Close off the embed with <hr> and you're set - a beautiful sidebar with the live BTR player throughout your site.
For more on custom theming with NationBuilder, check out our "How to Custom Theme" screencast. And for more tips on customizing your sidebars, see this great post by Richir Outreach.