safariextensions:

Beautipedia is an extension to make Wikipedia a better environment for reading articles.

Reminiscent, in some ways, of Instapaper Greystyled translated to Wikipedia. It uses jGaramond which—while not as attractive as some other Garamonds out there—has broad Unicode character support. It doesn’t indicate which words and phrases are links until you hover the mouse over them, which may be a blessing or a curse depending on how you use Wikipedia.

Looks great for an afternoon of reading, but as Jonas mentions, the lack of distinguishing features for links could be a deal breaker.