keywords-directory DOT com doesn't seem like a valuable domain to me, since (a) it has a dash(s), and (b) it maybe a long name.
You could have just made pages of links, and monetized with Adsense, to see if it made more money than the registration cost. I did this years ago and my directory (lists of links) did ok. Google loosely recommend a maximum of 100 links per page. You basically put together a list of website urls, and grab their description meta-tags to use for the content of the page. Like DMOZ.org does. The HTML tags DT and DD are useful for this.
My forum signature is under construction.