Axialis IconWorkshop™ Lite for VS 2008
No, I haven't totally lost my mind and gone completely marketing mad. This is a free add-in to Visual Studio 2008. Microsoft worked with Axialis to create this tool because there is a need for new, larger icons, now that we have higher resolution monitors. IconWorkshop supports creating 256X256 icons supported on Vista.
You can download the free add-in from the Axialis site: