Apparently, it is the favorite of many people.
The OU currently has a poll up on their site, asking people what their favorite holiday is. The choices are Passover, Shavout, Tisha B'Av, Rosh HaShannah, Yom Kippur, Sukkot, Channukah or Purim.
The results so far (out of 4543 votes cast):
Rosh HaShannah 4%
Yom Kippur 5%
and leading with 27% and over 1200 votes... Tisha B'Av!
I can only attribute this to open tampering, as I highly doubt that 25% of Jews (even in a SLOP) would actaully list Tisha B'Av as their favorite holiday.
I'm kind of curious, however, about what the OU was thinking when they put that choice up there. I would sooner have put Tu B'Shvat than Tisha B'Av.