Modern Pictograms is a typeface made for interface designers and programmers. Designed to work on-screen at sizes down to 18 pixels.

Hand crafted, Infinitely scalable & Royalty-Free Icons for User Interface Designers. Three Hundred Twenty Four Unique Interface Icons

Sallee Design

315 royalty-free vector icons in EPS format - cheap

I can’t overstate the value of a good flat, sharp, detailed icon. You can style it any way you please, use it in a variety of projects, and communicate difficult interface concepts in a 16 pixel space. Considering the incredible amount of work that goes into designing each icon, and the quality exhibited below, these sets are scandalously low priced.

A collection of 100 pixelated camera illustrations for anybody to download and use in whatever way they see fit.

Map Icons Collection is a set of more than 600 free icons to use as placemarks for your POI (Point of Interests) locations on your maps. You can use them on Google Maps with the "My places / My maps" feature or automatically by using the Google Maps API.

These 100 monochrome social icons are designed with simplicity in mind. Provided in vector format, they are fully editable and scale smoothly. They are completely free, even for commercial use, redistribution or remixing

As with great works of art, you must look into the past to appreciate the future. With roots as far back as the 1970′s, the humble icon has come a long way. Following is a collection of icons though history. Although there have been many other operating systems in the time between 1981 – 2010, I’ve hand picked the ones of the most significance to modern icon design. These designs show just a small fraction of the icons in the many and varied User Interfaces throughout the years. To learn more about the history of User Interface Design you can find a comprehensive article on the subject on Wikipedia.

a list of highway shields for different locales. Includes particular state specific highway symbols like Kansas's exceptionally ugly yellow sunflower sign

Allows for browsing of icon sets - clearly displays license

Displaying the predefined icons that can be used for markers with Google Maps Google Maps Icons,ONLINE LINKS for official-placemarks: 

Icons for mobile apps. Designed and carefully optimized for iPhone & iPad apps, they're also perfect for Android apps, websites, t-shirts, tattoos and more. CC (free) version and paid version

Gentleface Toolbar Icon Set made for interface (gui) desginer. These icons can be used for wireframes and software mockups creation, websites and software applications toolbars and menus including iPhone and iPod apps. You'll find a set of 8 cursors and 236 icons in black and white color versions. The icons include pagination arrows, ratings and voting controls, social interaction symbols file system and text editor actions. The entire set totals 244 original icons optimized for 16x16 pixel size and available in 16x16, 32x32 and 48x48 pixel sizes. Royalty Free package includes vector icons in EPS and flash SWF formats for which you have full control to resize without loss of fidelity, color, and effects as you please.

monochrome

Free set of icons specifically designed for use as placemarkers within google maps

includes 178 web-related icons in a sophisticated and glossy design style. All 178 icons are available as 32×32 pixel PNG files

Web service that lets you generate an animated "loading" GIF with the foreground/background color of your choice. Icons have no licensing restrictions. Has a number of different styles and sizes to choose from.

Cute and clear icons to use in your nifty web application. They are licenced under a Creative Commons licence, so commercial use is fine. Also feel free to make derivatives with the included Photoshop documents.

Free set of 60 application icons in 16x16 format. Liberal license agreement for use in commercial applications

Large set of high quality CC-licensed applications available in 16x16 and 10x10

Silk web icon set, with 1000 icons , including report icons, some new picture icons, some small XHTML/CSS buttons, and some hardware drive icons. Licensed under creative commons

Collection of application/desktop icons licensed under CC and available in multiple sizes

Almost every application with GUI needs icons. And they better be sexy. And stylish. And consistent. And small. Here are few tips for programatically creating icons using Java 2D features

icons used in eclipse