I see really large footers on some popular sites with a lot of internal navigational links in them (such as Digg).
Are there usability studies or at least authoritative opinions on this topic?
Should I use large navigational footers in my future projects?
I would imagine it's little to do with usability and more to do with SEO. At least that's all I've ever used it for really.
I've never designed a site so that the user had to scroll to the bottom of the page to find what they were looking for, but I've put links at the bottom to help search engines find their way around.
In my opinion, the sweet spot is one line, two at most. The only things you need at the bottom of every page are the things that people will always need/want to do.
In the case of Stack Overflow, the only issue I have is that the feedback always welcome link intrudes on what contact us is for.
I'd keep the contact us and remove the feedback always welcome link.
I try to place links for using the site at the top of the page and links for help/info with the site at the bottom of the page.
Basically, the stuff people are using should be in the most accessible location while the stuff they may never need gets put at the bottom.
I honestly like the footer loaded with links both as a site user and site developer.
When you have a web site, there are always a whole bunch of pages you have to make that are difficult to categorize, and are used relatively rarely. Despite this, they are all very important pages that must exist. Good examples of these pages are the FAQ, the privacy policy, the contact information page, the terms of service, the credits/copyright information page, etc.
When you're making a site you want the navigation at the top to be all about the primary use of the site. If you stick links to these miscellaneous pages up on top, it makes a clutter. If you try to categorize them and put them on a separate page, it will frustrate the users who do actually try to find those pages. Also, regardless of any actual usability studies, Having links to these pages in the primary nav is aesthetically bad, in my opinion.
I would say that digg.com and newegg.com are examples of good use of the footer link blocks. The top navigation of Digg is all about digging, logging in, joining, searching, and just one link for "About". The top of Newegg is all about finding and buying products. All the extra stuff is down in a cluster of links in the footer. By putting those links in the footer of every page, you make them accessible, easy to find, but not intrusive to the primary experience of the site.
There might be a better way of handling all those pages that is better, but many popular sites are following this pattern. I think it is safe to assume that users are getting used to the footer links, or maybe they even expect them. If so, then there are definite advantages to following the same design.
If those links are useful or frequently visited, they would not have been in the footer in the first place. I think it's useful to keep as many links in the home page as possible. That's where most people start off on your website.
Usability-wise, I think it is a non-issue. I have no hard data on this, but having seen a lot of usability tests, I cannot imagine the presence of such a content-rich footer being a negative factor for users, unless the number of links is overwhelming, or worse, the design of the footer is incomprehensible (slipshod structure, obscure labelling, coding errors, etc.). SEO-wise, it would be a bad mistake to think that adding links in that way would up your page-rank score in any way. It may in fact penalize it if Google thinks you are trying to cram a bunch of already present links at the bottom of the page. The most incredible use of the large footer concept can be seen in this French news site, which actually repeats the whole (yes, the whole) home page at the foot of every article page! Much too extreme, but apparently very popular.
footer links pro's & con's
Pros: 1. Shortcut to pages 2. Navigation source on scrolling pages 3. Can give site overview (like site map)
Con's: 1. Too many links are a waste of time & creates clutter i.e. 7 +- 2 chunks is the limit 2. Indicates poor navigational structure (usually depth of navigation) - if users cannot find it with the main menu easily, you have bigger issues than footer links! 3. Very few users look for these links - usually only advanced users who are conscious of the purpose of these redundent links. Novice and newcomers to the site just wonder "do the links go to the same page?"
i would suggest use them as short cuts to key pages & frequently navigated pages. Limt to approx 7 links.
Some supporting literature:
Better literature is available in usability papers & research. So if you researching this issue have a look at some academic output.