On my Motorola Droid, there appears to be no way to assign different ringtones (notification tones) to different calendar events. It only allows one notification tone (the selected default, which I currently have set to Captains Log.) for the entire calendar. WHY? My old LG-VX8700 phone allowed any of the 330 ringtones on the phone, to be assigned to any of the calendar events. Not so on the Droid! ARGH! 
If I have to complete a particularly awful job or attend a particularly awful meeting, I like to use Bart Simpson’s "I didn’t think it was physically possible, but this both sucks and blows." For normal meetings or appointments where I want to make sure I’m punctual, I like to use this from Capt. Gideon from the Babylon 5 spin-off Crusade: "Mr. Wells: ‘30 seconds to spare.’ Gideon: ‘I’m a punctual kind of guy.’" For my dog’s appointments at the Vet., I have a ringtone of a bunch of miscellaneous dogs barking (like at the Humane Society). To remind me to give my dog his meds. (e.g. Heartworm pills), I have a German Shepherd Dog barking, because my dog is a German Shepherd Dog. The Motorola Droid does not seem to allow this flexibility,
Also, it appears that I’m going to need a directory on the SD card for ringtones and a separate directory for notification tones, and the MP3 files copied to both directories, taking up twice the space. WHY? This is a model of inefficiency.
