Properly spelled "Volapük," which is Volapük for "world language." Strangely enough, the source language for the words that make up "volapük" is English: "vol" is from English "world" (which it translates), and "pük" is from English "speak/speech"---which gives you an idea of how horribly Volapük would mangle words as it incorporated them into itself. Most are barely recognizable.
The language itself is interesting enough in its own way. It's been said that you could conjugate a verb in Volapük in over 50,000(!) ways. I did a little back-of-an-envelope calculation once: that isn't far off. Basically because of all the various prefixes and suffixes that can be put on independently, giving a combinatorial explosion. You can say something like «pulöfofs-öz!» which means something like "I command you women to have been loved (by some time in the future)!" --- a future perfect second-person plural feminine passive jussive (strong form of imperative). Ow. And I haven't even gotten into the aorist forms. It's got all kinds of crinkles and knobs, that language; it's like speaking Norway (the country, with all the crinkles on the edges, not the language Norwegian).
Infighting among its supporters really spelled trouble for the language's success. Johann Martin Schleyer, the inventor, believed that the language was divinely inspired and that he alone had the authority to determine it. But even during his lifetime there were more streamlined forms being developed and taught, and many basic aspects of the language were changed from his original design (even the alphabet). The arrival of Esperanto on the scene was the death-blow for Volapük, which just couldn't compete. It survived in small numbers here and there, and later an attempt at reviving it was made in 1931 by Arie de Jong, who developed what is known as "Volapük nulik" ("new Volapük"). He made some pretty radical changes to the lexicon and spelling, and also some deep changes in the grammar itself. So to me there are really three main dialects of Volapük: the pure, true, Schleyerian original, the slightly later, streamlined versions popularized and adapted by Kerckhoffs (both called "Volapük rigik"/"original Volapük," but that generally means the Kerckhoffs-style version, since Schleyer's style never really caught on with anyone), and de Jong's Volapük nulik.
There's still the odd web page out there in Volapük, if you look around...