I tried it with http://plato.stanford.edu/entries/sartre/ and got the message: "You are now a certified Document Cyborg hacker, but you don't get any files:)"
Nice service. Only advice I can give is to tweak the typography a bit for the PDF output: I'd restrict the measure (line lengths) to around sixty characters, and boost the leading (space between lines) to about 1.5 times the line-height. Personally, I'd make the body text a bit smaller too, but the bigger text might be preferred by some.