Splash Screens Are For the Birds
They are legacy website design creations. During the boom, splash screens showcased 2 things: 1) How great and expensive the designer of the site was and how they knew how to use Flash, and 2) How expensive and great the designers that the company employed to make their website were. They are good for ONE TIME ONLY and then they are annoying and a waste of bandwidth, and time. Thx God for the "Skip Into" Buttons.
However, if your site is so cutting edge that it changes all the time, a splash page with a whats new section could be interesting I think. Of course dumping the viewer to an updates/news page is just as good with no extra-clicks.
Maybe a rotation of images displayed randomly, or something like that could make a splash page useful too, but I think they should go the way of the dinosaur and the Aztecs.
Viral marketing/movie/album sites are a different story though, those follow different rules.