I offer a couple of bookmark lists on my site, on topics like geographical data, Java image I/O libraries and useful Windows software. The topics are somewhat diverse, but mostly restricted to "all things computers". I've been doing this since the late 1990s, and such lists nowadays seem old-fashioned, very mid-nineties. Which is true. Yahoo! started in 1994 as a directory, basically a list of links to other Web sites categorized by topic (see the history section of Wikipedia's Yahoo! article). Nowadays their Yahoo! directory still exists but is only a minor section, not the first thing people think of when someone mentions Yahoo! A directory is not exactly flashy and has that boring feeling to it that all lists share. (With the possible exception of Top Ten lists on late night shows. Although, even there...)
Besides, there's Google. People who are new to the Net are used to search for sites with their favorite search engine, even if they know them. Even if they know the exact address. Typing in that address is in most cases more keystrokes than just typing in a descriptive word and picking the first result. Even if there is a bookmark list in the local browser, the search scenario is quicker than moving the hand from the keyboard to the mouse and picking the bookmark entry from a menu or sidebar. Google has its own directory, Google directory, which is basically the data from the Open Directory combined with Google's full text search. At one point, categories from that directory were part of the Web search result pages and the Google directory was featured on Google's main page like Images and News are today. Searches for a particular Windows mail client would result in a link to that mail client's homepage and in addition to the Google directory category Computers > Software > Internet > Clients > Mail > Windows because the client's site was listed in that category. That was great because it was an easy way of getting more choices, in this case mail clients. However, that category display features was axed, it was probably used too little by search engine visitors. My guess is that most of them never understood what they could gain from the category links.
Another side effect of the decreased importance of the bigger directories is a similar decrease in maintenance effort. Changes and additions submitted by users are sometimes dropped, or added only with a delay of weeks or even months. As a result, users give up on trying to help maintaining directories, and they use them less.
However, lists of links on a specific topic still have potential. In the beginning, such lists were created because search engines weren't good enough to find relevant matches. Whatever they used to rank sites, when you searched for image viewer, you didn't get a list of links to popular image viewing software. Then came Google, and in its aftermath, other improved search engines. But the Web grew, and Web spam became an issue, and the more specialized your search was, the more unlikely it became to get that list of relevant links. The problem wasn't that the good links weren't in the search engine's index, but the many pages that fought with them for high rankings and often pushed them away because they had some minor advantages which had little to do with relevancy to a particular query. That's why a well-maintained list of links about a topic is still (or: again) a good idea. With the help of search engines, such lists can be found if they are linked to by others who recognize their value. Maintaining such lists is simplified by user submissions. So if you have a topic you care about and have a good grasp on, don't hesitate to publish a bookmark list somewhere just because it may seem old-fashioned. You may do some people a big favor by sharing your knowledge.