Here is a TabBar Icons For Mobile Apps, which will help each iPhone or iPad application developer get his GUI in order. They are licensed under a Creative Commons Attribution-Share Alike license. You may use the icons for web design also.
Downloads: 25867 - Shareware - Download Now
The Business Icons Collection (XP) is a set of general-application centered XP Style Icons for use in software development and user-interface-design. It is one of many xp icon sets offered by VirtualLNK, LLC.
Downloads: 26313 - Shareware - Download Now
Powerful utility to replace icons for individual folders. You also can replace the system-defined standard folder icon, set an info tip for folders, rebuild the system icon cache and much more. Easy-to-use. The standard icon pack is included.
Downloads: 26374 - Shareware - Download Now
Original and professional web icons for your websites and software projects. Each web icon is available in four different sizes and six different extensions. It includes web buttons, toolbars icons, shopping cart icons, multimedia icons, user icons
Downloads: 26104 - Freeware - Download Now
16 x 16 Office Toolbar Icons pack contains everything you need for the toolbar of your office application
Downloads: 26413 - Demo - Download Now