This article is in two parts; Part I lists the uses from four sources and Part II presents thoughts from three sources.
Source 1: The Little, Brown Handbook by H. Ramsey Fowler, Little, Brown and Company,
i. Use the comma before a coordinating conjunction linking main clauses
note: some writers prefer to use a semicolon.
ii. Use the comma to set off introductory phrases and clauses
iii. Use the comma to set off non-restrictive elements: clauses, phrases, appositives
iv. Use the comma to set off parenthetical expressions
v. Use the comma to set off yes and no, words of direct addresses and mild interjections
vi. Use the comma to set off absolute phrases
vii. Use the comma to set off phrases expressing contrast
viii. Use the comma between words, phrases, and clauses forming a series and between
coordinate adjectives not linked by conjunctions
Note: This is from source 2:
Notice that the comma is usually put before ‘and’ and the last item. Some writers
disagree with this.
This is from source 3:
Michael Swan says in his Practical English Grammar: … they are often not used
between the last two items.
ix. Use the comma according to convention in dates, addresses, place names, and long
x. Use the comma with quotations according to standard practice.
xi. Use the comma to prevent misreading
e.g. Soon after, she left town for good. (for clarity)
The students who can, usually give money to the United Fund.
(to avoid a sense of incompleteness)
xii. (a) Don’t use the comma to separate a subject from its verb nor a verb or a preposition
from its subject, unless the words between them require punctuation
e.g. American, who are preoccupied with football, baseball, basketball, and hockey,
have not developed a strong interest in professional soccer.
One exception to these rules is that a comma may come between
S and V when there might otherwise be momentary confusion,
as for instance through two occurrences of the same word:
What his name is, is of no interest to me.
Whatever she does, does not concern me.
What one person may think of, another may not.
Rarely, a comma may also come at the point of gapping (cf 13.92f)
in an elliptical clause:
Rock aspires to recognition as art, and new classical music, to a larger following.
But more commonly no punctuation is used:
One bedroom was very large, and the other quite small.
“Finally, a comma is placed between a subject-verb sequence and a direct object in
indirect speech (cf App.III.21).
xii. (b) Ordinarily, don’t use the comma with words or phrases joined by coordinating
e.g. The sale of handguns, and other weapons is increasing alarmingly
© Don’t set off restrictive elements
e.g. Hawthorne’s work, The Scarlet Letter, was the first major novel.
(The title is essential to distinguish the novel from the rest of his work.)
(d) Don’t use the comma before the first or after the last item in a series unless a rule
e.g. The three TV networks, ABC, CBS, and NBC, compete constantly for
(e) Don’t set off indirect quotations or a single word quoted word unless it is a
e.g. To make something happen, repeat the magician’s word, “abracadabra.”
Source 2: A Comprehensive English Grammar by C.E. Eckersley and J.M. Eckersley,
“Your common sense and the desire to make your meaning clear
will often tell you where a pause is needed, …”
1. To mark off direct speech.
Source 3: Practical English Usage by Michael Swan
Source 4: A Comprehensive Grammar of the English Language by Quirk et al, Longman
i. If three or more clauses are coordinated but only the last is preceded by and or or,
commas (or semicolons) are required between the clauses, including the last pair
e.g. Prices fell, interest rates fell, and the employment figures rose.
The comma in such instances is termed a SERIAL COMMA.
(a) We sometimes have a choice between asyndetic coordination (without a
coordinator), in which case a serial comma is required, and syndetic
coordination (with a coordinator), in which case a comma is not required.
The most frequent occasions when this choice is available involve the
coordination of premodifying adjectives or adverbs. Thus, for adjectives we
may choose between  and [1a]:
He walked with long, slow strides. 
He walked with long and slow strides. 
If we wished to add further coordinated adjectives to , we need to place a
comma after each adjective except the last:
He walked with long, slow, steady, deliberate strides. [1a]
If we wish to add further adjectives to the syndetic coordination in , we
generally insert and before the last adjective in the series as in [2a]:
He walked with long, slow, steady(,) and deliberate strides. [2a]
(Such provision [1 – 2a] applies to adverbs as well)
(b) “The asyndetic coordination of  should be distinguished from the
hypotactic relationship of adjectives in , cf 13.2:
I noticed a large rear bench. [‘a rear bench that was large] 
Since large and rear are not coordinated in , we cannot of course insert
either and or a comma between the adjectives. Similarly, if we wish to
indicate not that the strides were both long and slow as in  and ,
but that they were slow strides which were long, we omit punctuation and
conjunctions, as in :
He walked with long slow strides.
© If we coordinate a series of three or more units, we normally omit the
conjunction and or or before all but the last unit. We of course insert serial
commas before all the units except that there is a choice as to whether to
insert or omit the comma before the conjunction. AmE generally favours
the insertion of the comma, while AmE journalistic style favours its
omission; in BrE, usage is divided.:
Dogs, cats(,) and other animals can recognize friends by smell alone.
Changes in human biological history is slow, steady(,) and progressive.
In the next two sentences we see examples of the use of the serial comma in
listing, irrespective of the linguistic status of the items listed. Again the
comma before the last item is optional, provided by and:
She bought eggs, butter, cheese, rice(,) and coffee.
He wrote down 73, 12, 41, 9, 7(,) and 13, and added them up.
Note: what has been said of the inclusive conjunction and applies to the
exclusive conjunction or (as in to or from town; by, with (,) or to a
person; butter, eggs(,) or fruit.