Since the very beginning, directories (of any kind) have had a very central role in the internet. (I have recently grown fond of Free Web Directory. Even Slashdot can be considered a directory: a collection of great news and invaluable user-generated comments. As far as software is concerned, doing a quick search on Google about software directories will return the free (as in freedom) software directories like Savannah, SourceForge, Freshmeat and so on, followed by shareware and freeware sites such as FileBuzz, PCWin Download Center and All Freeware (great if you're looking for shareware and freeware, but definitely less comprehensive than their free-as-in-freedom counterparts).