If you create backlinks to your own hubs from other websites, you potentially increase your hub's findability in the search engines. Backlinks are a sign for search engines that this site/page is of value. This will increase traffic to your hubs.
If you create backlinks to your other sites from hubpages, this will increase value and traffic to your own site once your hubscore is above 75. Try not to use more than 2 links to your website, if that''s what you would like to do. If your hubscore is under 75, your links have a tag "rel="nofollow", which means the links have almost no value for search engines. this tag disappears after you get 75 points.
If you link to other hubs from your own hub, this will increase your hubscore and will send traffic to those hubs you link to. It's good for your hubscore if you want to keep it above 75.
Hope this helps!