Filing closes on November 2 for the New Hampshire presidential primaries. 21 Republicans have filed; 23 Democrats have filed. Anyone may appear by filling out a Declaration of Candidacy and paying $1,000. It is conceivable that a few more names will be added, since there is another hour left to file.
For a list of the candidates and contact info for each, see this page from the New Hampshire Secretary of State’s site.
In 2004, there had been 23 presidential candidates on the New Hampshire Democratic primary ballot, and 14 on the New Hampshire Republican ballot.
Long-time Secretary of State Bill Gardner has said in the past that New Hampshire voters are not confused by facing this many names on the ballot.