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Are those URLs (or URLs like them - I realize they're just examples) actually being used in internal links, or are you just saying that they all resolve? The case-sensitivity thing isn't a huge issue, and the canonical tag would work well for that. Otherwise, you'd have to 301-redirect every possibly version (and 98% of them will never be used). I'd really focus on fixing the internal links first, and then 301 or canonical the versions you used internally (or that have inbound/external links). For the "Default.aspx" version, I think 301s are a little better, but ASPX can be a bit persistent about that, so it's a bit hard to advise. Sometimes, you are constrained by the platform. The biggest difference is that a 301-redirect will also redirect people, so they'll be more likely to link to the proper version. The canonical tag only impacts Google. Both work reasonably well, though, and do pass on most link-juice if used properly.

By part of the navigation I was referring to a primary page on your site. For SEOmoz, navigation pages would be Campaigns, Research Tools, Q&A Forums, etc.

Howdy, Depends on your definition of self-referencing links, as there are several degrees. Internal links, pointing from one page to another On page anchor links, simply pointing to another part of the same page, usually for navigation purposes Truly self-referencing, where a link simply points to it's own page in an attempt to trick a search engine. Normal internal links (1) are an important part of any website and give search engines important clues about relevance, site structure, and how to flow signals like PageRank. Internal links are very important for SEO, but also the most easy to abuse, so you can get yourself in trouble if you overdo it with aggressive over linking or over-optimized anchor text. And keep in mind that while internal links are important, they don't pack near the punch as authoritative external links. Internal anchors (2) such as http://example.com#football are also important for navigation, and Google does use them often for clues about content and structure. You'll often see internal anchors show up in search results, especially for sites like Wikipedia. Finally, I don't see any value in the truly self-referencing link (3). A page that points to itself seems like a mistake, and using it to game a search engine is most likely a bad idea. As for authoritative sources, you could look at the 2011 Ranking Factors, which shows that the # of internal links on the page is fairly correlated with high rankings. (and notice the anchor in that link, as well Hope this helps! Best of luck with your SEO!