I recently posted a comment to a question with a link, and I noticed that it is very difficult to tell that there is a link there. The color of the text and the color of the link are very hard to distinguish in a comment.
Here is a screenshot of what I'm talking about:
On my monitor at least, it is very hard to distinguish.
Looking at the CSS, the regular text appears to be at #444444 and the link text, when not hovered, is at #3A79A6.