When I did a recv after getting something back from select, I consistently got empty (i.e. zero byte) responses. Though I'm not entirely sure what is supposed to happen here, this does make some kind of sense to me -- select is saying "yeah, the socket's there, go ahead and read from it," even though there is no data presently waiting.

As for books, I highly recommend UNIX Network Programming by W. Richard Stevens, and Douglas Comer's Internetworking with TCP/IP (Vol. I covers the basic, low-level stuff). Not exactly light bedtime reading, but they will give you a solid understanding of what lies beneath all these slick perl modules.