Some of the things I've made that I think other people could use are listed here. This list is quite incomplete, and I will (hopefully) add more projects/pieces of code in the near future:

Java:

• JTabbedComponent - An easy way to add a GUI object with tabs.
• UserInterface - Easily make windows and add components to those windows in Java.

PHP:

• PHP MySQL DB Class - A database class featuring a easy query function, demonstrating the singleton pattern and MySQL connection.
• Page Navigation Generator - A function that generates a list of pages. The list automatically readjusts and resizes based on the current page.
• eBay Connection Functions - A set of functions that make it easy to connect to the eBay API and retrieve live auctions. A parse function is provided to parse the returned XML from eBay and put important data into variables.