The succinctly named Photography by Barbara London and John Upton is hands down the Bible of photography.  Not only does it cover the technical aspectss of photography in great detail, but it goes in depth into the creative aspect as well.  This book was actually assigned to one of my photography classes and though I've taken many photography classes and read many other photography books since, Photography has always been the one that I turned back to.  The book is bulky, but it's well worth the read and a great reference for photographers.

If money isn't a problem, this book is available new in most bookstores for about $125.  If you're looking to save a few bucks though, you could buy it second hand and/or buy an older edition of the book.  The first edition was published in 1976 and covers everything you wanted to know about film photography.  The 2010 tenth edition of the book covers all of that and also includes an accompanying website as well as an obligatory section on digital photography.  Personally, I own the fourth edition of Photography from the 80's (back when the book was by Upton and Upton instead of London and Upton since they were still married!).  I randomly found it at a thrift store for $2 and you'll probably be able to find a used, older edition online for about the same price.  Though my older edition does not cover digital photography, it has really helped me understand photography in general, and thus, helped me with both my film and digital photography.