Stereotypical anime characters, usually the younger female ones, have large eyes (to portray innocence, I guess). But not all of them do. Sometimes they have crazy hair and crazy outfits and crazy actions. The voices are high because I guess Japanese people tend to have higher voices than Americans.
The people who watch anime aren't always those stereotypical geek/nerd/dork or whatever you wanna call them. Sometimes the people who do watch anime or read manga (Jap. comics) can get a little too into the culture, but hey, whatever.
Shoujo anime: Fruits Basket, Sailor Moon, Kaichou wa Maid-Sama, Lucky Star, Vampire Knight. I have mixed feelings about this genre. I very much like Fruits Basket while Sailor Moon made me want to smash my computer.
I don't know any Josei anime...
Seinen Anime: Higurashi No Naku Koro Ni, Elfen Lied, Hellsing, Ghost in the Shell. My favorite genre, although if you want to watch Higurashi or Elfen Lied be prepared for some serious gore and insanity.
Shounen Ai: Kirepapa, Junjou Romantica, Loveless. I know I said shounen ai is gay romance minus sex but JR has some intense guyxguy, just sayin.
Shoujo Ai: Strawberry Panic, Kannazuki no Miko, A Channel, Uta Kata. I'm not a yuri fan but shoujo ai's really cute ^^
Anime, in recent years, has enjoyed a significant boom in popularity in outside of Japan, namely in the Western world.
Although anime has interesting and unusual themes, sometimes adult (not common in most Western animation), anime doesn't really deserve the mass popularity it has gained. Most anime shows follow similar and repetetive plots and themes to eachother, and as well, anime technique on a whole is very primitive in comparison to the American school of classical animation (eg. VERY static characters, anime has walk cycles of 4 frames) and it seems the Japanese animators take as many shortcuts as possible. Humor in anime for the most part is insultingly simplistic; a character says something stupid, and everyone falls down. The sad thing is, most anime that tries to be humorous borrows the exact same gags as every other "comedy" anime.
However, there are a few artful gems which defy these stereotypes, (Miyazaki's films, namely) but on the whole anime is a overhyped genre thats sadly, killing North American cartoons off television.
Animation student: "You don't know what you are talking about kid."