A handy list of icons that can be used for all kinds of (non-technical) stuff:

For a good list (with large thumbnails) of Crystal Clear see here

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  Clock, the time, agenda, events
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  Favourite
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  Earth, the world, everything, global, multinational
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  Games
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  Creativity, painting, editing
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  The wikimedia family
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  Image:Nuvola apps kalzium.png
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  S
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  Education
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  Technology, technical things
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  Ideas, creativity
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  Music, sounds, audio
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  Information
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  Warning
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  Questions, more information, uncertainty
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  Ho stop, warning, don't do it
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  Stop
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  Add
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  Delete, remove
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  Close