When designing a user interface there are always times that you will find yourself using the same graphical element over and over. So in order to be more productive, it’s a good idea to keep a library of common elements such as form elements, buttons, icons, browser templates, and windows. Having these close by will save time and speed up your design and prototyping work flow. Here is a collection of these types of elements that should be a big help to you.
Here's some other articles that you will definitely find useful.