History is the only factor that makes underline the norm for links. If history had dictated that it was the BLINK tag would we still be using that … I doubt it …
IMHO, Links do not need to be underlined, but they should be treated differently than the rest of text on your site.
BUT
Underline does makes sense … people know it … Smashing Magazine has many different types of colored text that serve as links … so they use underline to distinguish what is a link.
I am a huge fan of Mark Boulton designs and articles, and while I know what is a link (so it must be working), i think bold black is not a good choice for a link, as there are times that it does not mean a link in his site. The new Yorker is an example where I am completely lost as to what is a link …
Take a look at this , this , this , this , or that and tell me that things that are links are not obvious !!
So I am torn …
I feel that you don’t need to make links underlined, BUT at the same time underlined links make things obviously links… If you aren’t going to be using underline to mean links … you need to spend a little time to make sure it’s obvious…