Most programmers have a collection of utilities and code libraries that they re-use for several projects.
I've created the PL/SQL Utility Library page on Google Code to host some generic utilities that I've written myself, some that I've collected from elsewhere (credits and links can be found in the relevant source code), as well as links to useful PL/SQL libraries that are actively maintained elsewhere.
Check out the links and download the source code, there's a lot of different stuff here; from parsing CSV files, integrating with Google Maps and generating JSON, to zipping/unzipping files with PL/SQL.
I plan to add several more packages as soon as I get the code cleaned up.
Drop a comment below if you know of any other PL/SQL libraries or utilities that should be added to the list!