Ok, here ya go:
Kidnappings can be REALLY fun if you get creative with it. First off, make sure they know that a kidnapping is going to occur (w/ some chapters, the Brothers know that "someone" is getting taken but don't know who, makes it more fun). Just tell everyone to meet at some location and let the fun begin! Once said person is taken, you usually bring them somewhere that's fun or entertaining, based on what their personal interests are. Like, if the people you're 'napping are video game freaks, bring them back to your apartment w/ a PS2 or something, if they love Lord of the Rings, take them somewhere to watch the movie (should give you plenty of time

). While you're keeping the person "entertained" the rest of the Chapter is out looking for them. When they are taken, you leave behind a single clue, which leads them to some other location, w/ another clue, and so on and so forth until finally, the last clue leads to where the person is being held captive. It's usually fun to all go out to eat or something afterwards, and talk about what went right or wrong.
Now, you can get REAL creative with this. In the past I've known people that have done this, and clues were everything from handwritten notes to codes, to riddles, puzzles, video clues, computer programs in C++, and even a strategicly planted cell phone which rang when the group arrived at the location!
You could even get other ogranizations in on it, have the group sing a song or do a dance to get the next clue, the sky's the limit!
The only suggest I have is to make it so that everything is in walking distance. Use a car to initially "kidnap" the person, but restrict their usage after that... it's been my experience that a car chase ALWAYS will follow... especially w/ the fraternities.
Hope that helps, and have fun! E-mail me or IM me if you'd like some more suggestions, I don't really wanna put everything in here.