Differentiating Visited Links

Keeping on-topic with web design and Jakob Nielsen's recommendations, he makes the point that a key part of the web's UI is that links can show you when they have been visited. He recommends that visited links appear in a darker, more subdued colour* than the normal links.

I've recently come across two designers who have looked at using some of the features of CSS to make visited links even more obvious:

CollyLogic: Ticked Off? Visited Links How-To
Simon Collison shows how to use background images to create a visited "tick" to the right of your links.

Mike Davidson: Making Visited Links Radical
Mike Davidson takes a different approach and uses the radical √ symbol to indicate when a site has been visited.

Both make the point that this method may not work for everyone, or for every link. For a start it can clutter up your body text and make it harder to read, but it can also confuse users as it is a non-standard implementation of the standard visited links UI paradigm (which is a big no-no according to Jakob Nielsen).

Jakob's got a point - I know that I get confused by these sorts of UI changes, and will probably ignore them when surfing for information. Once this sort of change has been adopted by enough sites, then it becomes a de facto standard and then it is OK to use as most users will be aware of what it means.

Another example of this sort of UI change is having some way of denoting when a link goes to an external site. The SSW website does this by placing a small blue globe and red arrow next to links that go away from their site. I found that confusing, but at least I wondered what it was before trying the link, and thus worked out what it was.

Perhaps the visited link UI change would work better if it showed me an empty checkbox next to the link before I clicked on it, and then ticked it afterward. At least that way the user would work out what it was a bit faster. (another idea was to strikethrough the text once the links is visited)

On the other hand, Jakob suggests that designers early adopt the Title attribute in anchor tags to show users more information about a link in a tooltip. Mostly this is because it doe snot harm users whose browsers don't support it, but also because it does add value to links. I've used it myself in the links above - did it work for you?

[* Note: I am using Australian English spelling, hence the "-our".]