| http://www.w3.org/ns/prov#value | - I am not sure how useful this will be for you, but I have put it to use in a couple of web-apps, including here, and here (that second one is part of a benchmarking attempt pitting HDBC against MongoDB and AcidState, so you can use it to see how the three compare implementation-wise in the context of a Haskell web-application).
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