You probably know that the summer solstice normally occurs on 21st June.
But did you know that in 2008 the exact solstice will occur at 23:59 UT on 20th June?
In fact this is the first time since 1896 that it hasn't occurred on 20st June, and since 1975 it hasn't occurred on 21st June[1].
So this will be the longest day, specially in north countries where it's difficult to find dark night ;-) A good occasion to run a nightly race, called St. Hansgaloppen for about 14,5 km in the nature; sounds great.
Notes
[1] In 1975 it was on 22th June.