Complete schedule of the 2012 Republican presidential primaries

When is the next Republican presidential primary? Here you go:

January 3, 2012          Iowa (caucus)
January 10, 2012        New Hampshire (primary)
January 21, 2012        South Carolina (primary)
January 31, 2012        Florida (primary)

February 4, 2012        Nevada (caucus)
February 4–11, 2012  Maine (caucus)
February 7, 2012        Colorado (caucus)
                                   Minnesota (caucus)
                                   Missouri (primary) - Per the Houston Chronicle: "Voters can cast ballots that day, but Missouri Republicans will use a caucus process starting in mid-March to select their delegates to the national convention."
February 28, 2012      Arizona (primary)
                                   Michigan (primary)

March 3, 2012            Washington state (caucus)
March 6, 2012 - Super Tuesday
                                   Alaska (caucus)
                                   Georgia (primary)
                                   Idaho (caucus)
                                   Massachusetts (primary)
                                   North Dakota (caucus)
                                   Ohio (primary)
                                   Oklahoma (primary)
                                   Tennessee (primary)
                                   Vermont (primary)
                                   Virginia (primary)
March 6-10, 2012       Wyoming (caucus)
March 10, 2012          Kansas (caucus)
                                   US Virgin Islands (caucus)
March 13, 2012          Alabama (primary)
                                   American Samoa (caucus)
                                   Hawaii (caucus)
                                   Mississippi (primary)
March 17, 2012          Missouri (caucus) More on Missouri's confusing GOP vote/caucus here.
March 18, 2012          Puerto Rico (primary)
March 20, 2012          Illinois (primary)
March 24, 2012          Louisiana (primary)

April 3, 2012              DC (primary)
                                   Maryland (primary)
                                   Texas (primary)
                                   Wisconsin (primary)
April 24, 2012            Connecticut (primary)
                                   Delaware (primary)
                                   New York (primary)
                                   Pennsylvania (primary)
                                   Rhode Island (primary)

May 8, 2012               Indiana (primary)
                                   North Carolina (primary)
                                   West Virginia (primary)
May 15, 2012             Nebraska (primary)
                                   Oregon (primary)
May 22, 2012             Arkansas (primary)
                                   Kentucky (primary)

June 5, 2012               California (primary)
                                   Montana (primary)
                                   New Jersey (primary)
                                   New Mexico (primary)
                                   South Dakota (primary)
June 26, 2012             Utah (primary)

To be determined        Northern Marian Islands, Guam

There's much more detail over at Wikipedia, including whether each is an open or closed primary, and how many delegates there are per state.