Tomorrow is the Summer Solstice in the northern hemisphere and the Winter Solstice in the southern, so it is either the longest day of the year or the shortest. If you wish to celebrate this fact then these Google Maps mash-ups could prove useful in working out when the sun rises and when the sun sets.
EarthTools lets you check the time of the sunset and sunrise anywhere in the world by setting your location on a Google Map.
The Daylight Map is a Google Map that shows where it is currently daytime and where it is night-time in the world. Areas where it is currently night are shaded out on the map. The night-time areas also show the effects of light pollution from electric lights. Daylight Map also has a Cloud Cover map showing current cloud cover around the world.
Hey, What's That? - Cosmic Visibility
If you select the Earth tab on The Cosmic Visibility map you can view a day / night layer on Google Maps. You can change the date and time to see when and where there will be daylight. The map comes with a very handy (for the northern hemisphere) 'summer solstice' quick link to see where the sun will be on the solstice.