Seeking pretty icons for GIS development?

These are the icons used in the latest QGIS (by default I think) and GRASS GIS:

They are licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License which means you can use, alter and share them as long as you attribute the original creator and share your icons under the same or similar license.

Other commonly in web-based GIS application used icons are the GeoSilk icons by OpenGeo:

This icon set is licensed under Creative Commons Attribution 3.0 License which let you edit and share the icons as long as you attribute the original creator.