My favorites for basic knowledge:
The Morrow Guide to Knots by Mario Bigon and Guido Regazzoni
and
Knots by Peter Owen

Both have excellent illustrations/photos with most basic knots and some exotic ones. Great for sitting with various cord lengths and practicing through the winter!

Get a set of "Knot Playing Cards. I got mine at Campmor.

That would seem to cover the majority of knot needs IMO.

A few months ago I went to tie a taut line hitch and could not recall how. So now I have a piece of paracord in my shirt pocket to practice knots. I like the Zeppelin bend as well. Has a cool name to it.

I would point out that a square knot is easy to upset if you pull on a tag end while it is under tension.

IMHO, a square knot is useless in any significant application - highly over rated.

Rbruce, I would add a fishermans knot, or bloodknot, to that (I think they are the same knot).
Hikermor, the square not is great, when the lines are under tension. I have used it many, many times, backing it up with a half hitch, for climbing, and general knot tying around campsites. Its easy, and secure, when used for the applications the know is intended for.
IMHO, there is no real reason to learn more than 9 knots-other than for fun. If what you are trying to do cannot be done with the knots that rbruce has listed, then you are either in a REAL bad situation, or you're a sailor .

On that topic, I recall reading about the old whaling days, and all the pirate and pole exploration books that boys read when young (or used to), and I was always fascinated that sailors knew how to tie these intricate knots, and knew for what applications. I used to think it would be cool to be a sailor, just to learn the knots! Ah, the simplicity of youthful dreams!

Missing from this list is a good bend ("bends" are used for joining two ropes together). The "Sheet bend" is a bend, but not a terribly good one IMHO. There are others that are much better. A "Hunters bend" (a.k.a. "Riggers bend") is far superior. As is the very similar "Zepellin bend". My favorite bend is the "Shake Hands", but you rarely see this one documented.

For hitches, my choices are "Round Turn and Two Half Hitches" or a "Slipped Constrictor Knot". The "Constrictor" is the best of all binding knots IMHO, and it can also be used as a hitch. But if you ever want to get it to let go of what you tie it to, you better slip it! The Clove Hitch isn't bad, but only so long as your direction of pull on it remains constant. Pulling it from either side or "unrolling" it can lead to failure. The "Buntline Hitch" is good too, but can be difficult to untie after severe tightening.

Great suggestions and I'll check out some of the books and pocket guides mentioned. I am familiar with the Grog site. I have practiced a few and am already familiar with others. As far as schooling goes I just want to be ahead of the game and come into it with some knowledge already in my corner. you can never be too prepared. Thanks to you all!!

I am glad you have survived the use of the square knot and not had an accident. I am quite serious and I am not trying in the least to be funny or sarcastic.

I looked through some of my references for mention of the square knot, so I could offer something besides my own opinions. Three of my more modern references didn't even mention the square knot; another only listed it in a table, offering that a square knot reduced the strength of the rope to about 43-47% (compared to 80% for a figure eight). Finally in a 1942 publication I found the following "For joining two ropes a fisherman's knot...will be found better than a square knot... and is easier to undo afterward."

The generally preferred knot for joining two ropes together, as say to establish a rappel, would be the double fisherman's knot; some use a variation of the figure eight for this application. I would not quibble at seeing a double sheet bend applied to this purpose but I would never put body weight on a rope joined with a square knot.

I began technical climbing around 1957, later including vertical caving and technical rescue, being particularly active from around 1965 to 1985. Even now as a geezer, I still do the occasional rappel to retrieve a juicy paleontological specimen. In all this time, I have never heard or read of anyone advocating use of a square knot for any technical purpose, with the single exception of the quoted reference above.

What I have observed over time is the greater detail paid to knot tying, the increasing use of more secure variations of knots (such as double loop bowlines for the standard bowline), the better analysis of accidents, and the universal precaution to back up every knot tied with two half hitches or the equivalent. A lot of this has to do with the now universal use of synthetic materials in climbing ropes compared to the manila or hemp ropes in use until after World War II. Some of the more recent synthetics (Spectra and Dyneema) don't knot well at all and must be sewn or knotted with a triple fisherman's knot - the characteristics of the rope must be considered when deciding upon the appropriate knot to employ.

Here's a list of reviews of knot-tying books:
http://www.earlham.edu/~peters/knotlink.htm#bookstore
which includes sections on rope rescue knots:
http://www.earlham.edu/~peters/knotlink.htm#roperescuebooks
and climbing knots:
http://www.earlham.edu/~peters/knotlink.htm#climbingknotsbooks

The square knot is a binding knot. That is what it was intended for. In that use it is good. It is NOT however, intended to bend (join) two ropes together. It is absolutely terrible for that purpose, whether kept under tension or not. The fact that you've suggessfully used it for climbing is nothing more than luck. Each time where you lucked out before you could have just as easily been a Darwin Award winner instead. I am not saying this to sound belligerant, but the square knot has probably killed or injured many people by being improperly used as a bend than any other knot. But don't trust me - go read any reputable knotting book and find out that every knotting expert says the same thing about the square knot. It is neither a strong nor a secure knot. Its good enough if you're just tying a bundle of newspapers together. But don't use it for anything more critical than that.