Call it tail envy. With only a vestigial nub to show for ourselves, perhaps it's no wonder that animal tails capture our attention. The following Web sites present some of the more interesting tails to be found in the animal kingdom. The first Web site contains a recent article from Discovery News describing new findings that at least one species of scorpion produces two distinct types of tail venom, which have completely different effects on their victims (1). The next site from Singapore Zoological Gardens introduces the cebids (our New World monkey cousins), some of which have amazing prehensile tails that are used like a fifth limb (2). The rattlesnake is another famously-tailed creature, highlighted in the following site from the Arizona-Sonora Desert Museum (3). The site covers the main aspects of rattlesnake natural history, including a section on how the rattle forms. The Great Plains Nature Center in Wichita, Kansas, offers a Web page devoted to the beaver, including tail trivia and an audio clip of a resident beaver surprised in his den at the Kansas Wildlife Exhibit (4). Anyone who has witnessed the freakishly fascinating spectacle of a gecko leaving its tail behind to distract a would-be predator will appreciate this brief bio of the Tokay gecko, presented by ReptileCenter.com, the Herpetologist's Portal (5). Stacy's Wag'N'Train -- offering dog-training classes in San Jose, California -- provides this online guide to dog body language, which would have a very limited vocabulary without the tail (6). So, how did the peacock get its tail? It's a simple question that has driven zoologists crazy for over a century. The next Web site (7) contains an in-depth article on the subject from the Independent (London), offered through National Geographic News. And finally, the bizarre gulper eel -- able to tie its tail in several knots -- gets is own Web page on Pangea, the Web server for the Department of Educational Leadership and Technology at Southeastern Louisiana University (8). This deep-sea curiosity uses its bioluminescent tail tip to lure hapless prey into its impossibly gigantic mouth.