• NaProMo
  National Procrastination Month is by far the largest community challenge project, with participants throughout the world (though most participants don’t even bother signing up). All you have to do is put off whatever you can put off, until at least the beginning of December. It’s also the oldest community challenge, predating NaNoWriMo by millennia. In fact, recorded history began when an ancient participant failed the challenge.
• NaMoGroMo
  National Moustache Growing Month, otherwise known as Movember, challenges participants to let the mo gro. Women are encouraged to participate.
• NaNoMoMo
  National No Moustache Month challenges the partners of NaMoGroMo participants to convince them to shave the mo.
• NaNaGaMo
  National Navel Gazing Month invites participants to ponder, mull, ruminate or philosophise over an existential, theoretical or theological question, for the entire month. Extra points are given if the participant:
  • Achieves nothing else in the month, except basic maintenance of their earthly vessel
  • Is able to convince someone else to take care of the basic maintenance of their earthly vessel
  • Frequently refers to the work of an earlier philosopher they’ve read
  • Frequently refers to the work of an earlier philosopher they haven’t read
  • Spends the month arguing the same point with the same person, to no conclusion
  • Ends the month with exactly the same opinion
• NaPerMeMo
  National Perpetuate a Meme Month invites participants to spread Internet memes, via blogs, emails, IMs, and particularly by describing them to others in person. Extra points are given if:
  • The meme is more than a year old
  • The participant doesn’t check other sources to see if the meme is pure bullshit
  • The participant creates their own derivative example of an existing meme (such as their own Lolcatz photo, or Demotivator)
• NaTeYoFriYoPlaMo
  National Tell Your Friends Your Plans Month is very popular amongst young people, especially college students. Participants are encouraged to tell their friends what they plan to achieve in in the short and long term. Extra points are awarded if the plans require extraordinary serendipity, divine intervention, or a suspension of the fundamental laws of the universe. Bonus points are awarded for returning participants if they haven’t achieved any of their plans from the previous year, and if they have all new plans this year.
• NaWhiAboDePubMo
  National Whine About the Death of Publishing Month encourages participants to engage in lengthy discussions about how publishing is going to hell in a handbasket, and to make predictions about when the industry will collapse and society will abandon reading altogether. Now in its 400th year! Extra points are given if the participant:
  • Uses the example of a bestselling book they think is bad as evidence that human civilisation is on the verge of self-destruction
  • Uses their own failure as a writer as evidence that the publishing industry doesn’t know literature from a pile of manure wrapped in a tabloid
  • Fails to see the irony in their refusal to buy any more books until the industry lifts its game
• InIOToLiAmAgMo
  International It’s Ok To Like Americans Again Month launched only this year – November 4, to be exact – and already it has millions of signups worldwide. Participants are encouraged to openly discuss American politics without shaking their heads in disbelief, to see American movies, read American books and listen to American music without feeling ashamed, and to give American tourists the opportunity to prove themselves to be boorish assholes, instead of simply assuming it.
• NaNaNaNa-NaNa-NaMo
  National Sing Along Without Knowing the Words Month – If you get through an entire song without anyone noticing, you win. You’ve been participating for years.
• NaIDoThiThaFuMo
  National I Don’t Think That’s Funny Month challenges participants to write to so-called satirists and comedians, and explain exactly why their brand of humour is wrong, illogical, unacceptable, dangerous to children and generally devoid of value or place in civilised society. Extra points are given if the participant:
  • demonstrates a complete misunderstanding of the concept of satire or comedy
  • reacts as if the piece was intended seriously, and refuses to back down when they discover it wasn’t
  • insists that the benchmark for publication should be whether the participant thinks it’s funny
  • insists that satire is only clever or funny when it’s obvious or clearly labelled that it’s satire
  • insists that anyone who finds humour in the piece must be just as mentally retarded as the author
  • gives examples of other satirists or comedians they do understand in order to prove that the author isn’t funny
  • attempts to give their own examples of what satire or comedy really is in order to prove that the author isn’t funny
  • uses the word “sorry” sarcastically
  • claims to support the right to free speech while insisting that the author must voluntarily relinquish this right
  • threatens an organised boycott amongst the seven people they know
  • threatens physical violence upon the author, should they happen to wander into the participant’s basement
  • Complains anonymously, especially if doing so in a blog or forum the author will surely never read

Some of the challenges that didn’t make the Top Ten:

• NaBuSewMo — National Button Sewing Month
• NaCroSoMo — National Crossword Solving Month
• NaSoKniMo — National Sock Knitting Month
• NaRhiNoMo — National Rhinoceros Month (If you see a rhino, you win. Very popular in Africa.)
• NaQuiPoOnYoBloMo — National Quit Posting On Your Blog Month
• NaCompAboBroIncoMo – National Complain About Browser Incompatibilities Month
• NaFaSoLaTiDohMo — National Scales Singing Month

November is also NaCreYoOwNaNoJoMo — National Create Your Own NaNoWriMo Joke Month. Please feel free to post your own contributions in the comments below. Extra points if your entry is vaguely pronounceable.