Regarding nofollow on content that you don’t want indexed, you’re absolutely right that nofollow doesn’t prevent that, e.g. if someone else links to that content. In the case of the site that excluded user forums, quite a few high-quality pages on the site happened not to have links from other sites. In the case of my feed, it doesn’t matter much either way, but I chose not to throw any extra PageRank onto my feed url. The services that want to fetch my feed url (e.g. Google Reader or Bloglines) know how to find it just fine.
Another tool to help you with your link building campaign is the Backlink Builder Tool. It is not enough just to have a large number of inbound links pointing to your site. Rather, you need to have a large number of QUALITY inbound links. This tool searches for websites that have a related theme to your website which are likely to add your link to their website. You specify a particular keyword or keyword phrase, and then the tool seeks out related sites for you. This helps to simplify your backlink building efforts by helping you create quality, relevant backlinks to your site, and making the job easier in the process.
Make it as easy as possible for users to go from general content to the more specific content they want on your site. Add navigation pages when it makes sense and effectively work these into your internal link structure. Make sure all of the pages on your site are reachable through links, and that they don't require an internal "search" functionality to be found. Link to related pages, where appropriate, to allow users to discover similar content. Denver Page Rank Click Here