Good SEO for each hub so they rank on google. Create a video version of your hub. Syndicate the video to video hosting sites. For each host you want to be sure you include a link to your hub or profile in the description box. Videos rank in google results so that is possibly more exposure and traffic.
Update the content of your hub with the latest information. An easy way to do that is set google alerts for the keywords your hub targets. You'll get fresh info on that keyword on a regular basis.
Recently I've been researching RSS feeds and ways to distribute them. Find out if you can turn your hub into an RSS feed and submit it to RSS feed directories. You'd get traffic from people subscribing to your hub. Check out feedburner
Another RSS tip. Record your hub as an audio file. Use audioboo.fm to upload the audio and get a RSS feed. Turn that feed into a podcast that you can upload to itunes.
Backlink to your hub through your blog and other backlinking strategies.
Post your hub to all your social media profiles.
Post comments on other hubs and answer questions. Sometimes that will get people to visit your hubs and read your articles. Don't forget to follow hubs that you genuinely like. You might get a follow back also.
I wish you the best of luck on your hubs and hope this info is helpful.