It's possible to link and/or append mats from various .blend files. But at this moment there's still no way to browse it. (In the visual sense. So you're either relying on memory or guessing by the name.) Supposedly there is an add-on being worked upon to do that kind of thing and allow you to have a proper library, but I don't recall the exact name. (Still very early in development last I heard.)

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Barbequed Pixels?

Your friendly neighborhood Wings3D nut.
Also feel free to browse my freebies at ShareCG.
There might be something worth downloading.