See Builder, Boomer, X, Y below.

  Because women tended to get married earlier, maternal lines have more generations in a given time. e.g. Anna Price (an ancestor following a purely maternal line) was born in 1750 and is generation 10; Thomas McBride (a paternal line) was born in 1749 and is generation 8.
  The average family for generation 6 spanned 20+ years (from youngest to oldest child), so the generation boundaries spread out as you move forward and backward from generation 6.
  There are about 200 generation 2 descendants of these California Settlers with birthdates from 1949 to 1998.

Birth-dates

Gen Median  Range
  1       1978-present
  2  1971 1949-1998
  3  1945 1922-1970
  4  1915 1896-1933
  5  1883 1865-1895
  6  1853 1839-1863
  7  1820 1789-1845
  8  1798 1749-1822

|Gen   Range
|  9  1729-1805
| 10  1698-1764
| 11  1673-1735
| 12  1637-1709
| 13  1590-1668
| 14  1567-1655
| 15  1540-1620
| 16  1515-1573
| 17  1483-1538

|Gen   Range
| 18  1442-1503
| 19  1420-1470
|  See Finley Ancient Roots for
|  speculation on dates below.
| 30  950-1000
| 57  14 AD
| 98   1700 BC
| 125  2,350-2,900 BC Noah
| 134  3760 - 5200 BC Adam

There isn't much of a consensus on generation definitions. There are 3 or more different date ranges for the generations.
The Boomer Generation defined by the Census Bureau as the high birthrate years (1946-64), but other sources use 1943-1960.
The Silent generation was coined in the November 5, 1951 cover story of Time to refer to the generation within the United States coming of age at the time (born from 1923 to 1933).

The generation after Gen X has been called Gen Y, the Net Generation (N Gen), Echo Boomers, Mosaic, the Bridger Generation and the Millennial generation.

Here is a list of the years and generations

1927-1945 - Silent Generation or Traditionalists
1946-1964 - Baby Boomers
1965-1983 - Gen X or the Busters
1984- 2002 - Gen Y or the Millennials
2003- Current Gen Z or the Digital Generation

Silent Generations - born around, or parented by, those of The Great Depression of 1929 & children of the WWII gen.; marriage is for life; labor union generation; Korean and Viet Nam War generation; in grade school, the gravest teacher complaints were about passing notes and chewing gum in class; readers; the Big-Band/Swing music generation; strong sense of trans-generational common values and near-absolute truths; dsiciplined, self-sacrificing, & cautious.

Baby Boomers - the "me" generation; "rock and roll" music gen.; ushered in the free love and societal "non-violent" protests which triggered violence; self righteous & self-centered; buy it now and use credit; too busy for much neighborly involvement yet strong desires to reset or change the common values for the good of all; the first TV generation; quite conversational & skilled vocal & writer advocates; poor on marital skills...the first divorce generation; begin "gay toleration"...AIDS begins and is first lethal infectious disease in the history of any culture on earth which was not subjected to any quarantine what-so-ever because of a beginning obsession of individual rights prevailing over the common good...especially if it is applicable to any type of minority group; optimistic, driven, team-oriented.

Generation X - raised by the career and money conscious Boomers amidst the societal disappointment over governmental authority and the Viet Nam war and the scoff-law attitudes coming out of the protest times; school problems about drugs; late to marry (after cohabitation) and quick to divorce...many single parents; are iconographic...clothes lables are large & shows of caring (turning out for a worthy-cause rally) are fully sufficient expressions (while government, charities, agencies will see to the work of it); want what they want and want it now but struggling to buy; conversationally shallow because relating consists of shared time watching video movies; short on loyalty & wary of commitment; all values are relative...must tolerate all peoples; self-absorbed and suspicious of all organization; computer generation; survivors as individuals; cautious; skeptical, unimpressed with authority, self-reliant.

Generation Y - Facebook, MySpace, SMS and other instant communication technologies may explain Generation Y's reputation for being peer oriented and for seeking instant gratification. Generation Y, like other generations, is shaped by the events, leaders, developments and trends of its time. Members of this generation are facing higher costs for higher education than previous generations. Sources: class on "Connecting Across Generations"

Links:
Pre/Post-Modernism
Characteristics of the Generations
What are the cut off birth dates for the generations at askville.amazon.com
Generation Y at WordSpy.com