The "18th First Annual Ig Nobel Prize Ceremony" was held on 2 October 2008 at Harvard University. The winners of this year are:
Archaeology: Astolfo Gomes de Mello Araujo and Jose Carlos Marcelino, for showing that armadillos can mix up the contents of an archaeological site.
Biology: Marie-Christine Cadiergues, Christel Joubert, and Michel Franc, for discovering that fleas that live on dogs jump higher than fleas that live on cats.
Chemistry: Sheree Umpierre, Joseph Hill, and Deborah Anderson, for discovering that Coca-Cola is an effective spermicide, and C.Y. Hong, C.C. Shieh, P. Wu, and B.N. Chiang for proving it is not.
Cognitive science: Toshiyuki Nakagaki, Hiroyasu Yamada, Ryo Kobayashi, Atsushi Tero, Akio Ishiguro, and Ágota Tóth, for discovering that slime molds can solve puzzles.
Economics: Geoffrey Miller, Joshua Tyber, and Brent Jordan, for discovering that exotic dancers earn more when at peak fertility.
Literature: David Sims, for his study "You Bastard: A Narrative Exploration of the Experience of Indignation within Organizations". (Also see here.)
Medicine: Dan Ariely for demonstrating that expensive counterfeit drugs are more effective than inexpensive counterfeit drugs. (Also see here.)
Nutrition: Massimiliano Zampini and Charles Spence, for demonstrating that food tastes better when it sounds more appealing.
Peace: The Swiss Federal Ethics Committee on Non-Human Biotechnology and the citizens of Switzerland, for adopting the legal principle that plants have dignity.
Physics: Dorian Raymer and Douglas Smith, for proving that heaps of string or hair will inevitably tangle.
Here is an overview.