Select Artwork by Swatch
This is how it should work:
Select a Swatch in the Swatches palette, choose from the menu: 'Select all object that use this swatch' (as Fill / Stroke).
Comes in very handy to select items via the Swatches palette in complex cartoon style drawings. It is also a way to - kind of - create long awaited multi layer groups.

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KidCre8ive commented
I noticed that nothing happens when you right click a color in your Swatches window. Wouldn't it be amazing if when you did, you were given the option to select all fills or strokes in your document assigned the color? In my workflow, I will commonly need to see all colors used within a document, and I do so by selecting All and then hitting New Swatch Group in the Swatches window. I can then see every color, but if there is one in there that I need to quickly locate (I don't want to dig through layers) it's just not easy to do. This reverse-color selection model could be very quick and powerful IMO. It should list these three options in order after right clicking: Select All Fills and Strokes Containing Color, Select All Fills Containing Color, Select All Strokes Containing Color.
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Jan Vork commented
I would like to be able to select one or multiple Swatches in the Swatches palette, and then let Illustrator select all Objects that are colored with this particular Swatche(es).
In this way, I can replace e.g. multiple green swatches by one green swatch.
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Yes, true. A clumsy workaround we now have is to create a dummy object, fill and stroke it with a swatch, use Select Same Fill, unselect the dummy object, hide or lock selection (unless you have something already hidden or locked), select the dummy again, use Select Same Stroke, hide-lock this too, unhide-unlock... Just nonsense.
Meanwhile you can use a free script by Sergey Osokin to achieve this with a click:
https://github.com/creold/illustrator-scripts/blob/master/md/Select.md#selectbyswatches
At the moment it forces you to choose between stroke or fills, but not both, but I bet it can be improved.