Web Directories are designed to help webmasters and site owners find relevant directories. Unlike many other directories, these help the directory submitters (rather than the directory owners). They try to give you info that is helpful to you. Ultimately, you can use the information to make your own choice. If you are planning to submit to a specific directory, especially a paid one, do make sure if it's worth it. They don't carry as much PR power as they used to, especially with Google Caffeine coming up. If it's free then you don't have anything to lose like this web directory. Others that I'd recommend are DMOZ, Yahoo!, and of course Google' Directory .
Now what would be uber cool is for somebody to create an application that would allow you to automatically submit sites or webpages as you browse them. Just as we submit pages to facebook or twitter. But this'll do a lot more good for someone who's searching. Besides it'll help low PR sites to show up on google, which is good.