The 2008 set of national presidential nominating conventions (of the parties whose nominee could theoretically be elected) happens to work out on a schedule of one convention per month.
The Constitution Party meets April 22-27 in Kansas City.
The Libertarian Party meets May 23-26 in Denver.
Unity08 will choose its nominee in June (dates not set yet).
The Green Party meets July 10-13 in Chicago.
The Democratic Party meets August 25-28 in Denver.
The Republican Party meets Sept. 1-4 in Twin Cities, Minnesota
The Socialist Party will have its convention in St. Louis on October 19-21. That was left out.
Ooops…The Socialist Party convention is 2007, not 2008…Sorry