The first printing was released October 24, 1973.  This edition is still in print, so some are much more collectible than others.  Prices range from maybe $15 to about $200 (in collectible condition).  A first impression would occasionally go at auction for $275-300 shortly after LotR was made into films, but $150-200 was more usual, and only a Fine+ copy would bring $200 today.  There is a great deal of misinformation about these floating around the markets.  The copyright date is often given as the printing date, and the material on the cover and slipcase is often mistaken for leather:  none were ever issued in real leather.
 
A spelling error in the Dwarf runes on the cover exists on 1st, 2nd, and some 3rd printings.  All of these printings were ordered prior to October 12, 1973 - according to Hammond & Anderson (20,000 / 5,000 / 5,000).  Third printings were on retail shelves by February, 1974 (according to owner dated copies).  It seems that the majority of second printings were sold to lending libraries (when one is found for sale it is almost always ex-library), so second and uncorrected third prints are less common than production numbers seem to indicate they might be.
 
All printings up to fourteen have green marbled text block edges, though not all 14ths do.  I've seen later copies with light speckling (not giving a marble effect).  Discount outlet and book club editions have undecorated text edges, and those seem to be much more commonly found for sale online anymore.
 
Printing number is stated (see photos below) or indicated by a numberline through at least the 37th trade printing.  It would appear that the practice of numbering these was halted soon after the copyright was renewed in 1997 - possibly with the release of the Jackson films.  It is reasonable to assume that the number of printings, all editions taken into account, would be well into triple digits.
 
The 1987 50th Anniversary edition has a gold metallic finish to the boards and slipcase, with the decorations in green and red.  The trade anniversary edition has green speckled edges, but the vast majority of the ones seen for sale (95%, I'd say) are BCE/discount editions:  most have yellow top stain and three undecorated edges, many are blind stamped.  BCEs in fine condition are currently selling at about $20 [2009].  It would be difficult to assess the value of trade editions.  Many sellers fail to make a distinction, as most people who buy them are not the sort of collectors who would still be reading this, lol.  When I stumble across a listing showing green page edges, that copy will sell quickly if priced at up to $50.
 
In 1988 BOMC issued a large softcover using the same sheets, and displaying the same ISBN.  This is ridiculously hard to find online.  I've not been looking for it, but still... I do a fair amount of digging, and have not stumbled across one in nearly three years [2009].  There is high demand for this due to its scarcity, so if you're looking for it, you might have better luck at your local used bookstore.
 
All variants of this ISBN have been sold by BOMC and/or through other high volume distributors.  None are extremely valuable at this point in time.   A 1973 or 1987 printing has increased in value, and any numbered copy with marbled edges in collectible condition is worth at least the MSRP of a new copy, but, just my opinion... all the rest, and there are a very great many, are worth no more than the price of any ordinary used book (half retail).
 
The current list price for a standard edition is $35.  Though not so well built as the description seems to imply, they are very pretty, with much larger color plates of Tolkien's art than any other issue - scroll down for sample images.