X-Athlon

Modern olympics competitions are dominated largely by people who specialize in one area--for instance, long distance running, or weightlifting, or so forth. There are a few compound events, such as the biathlon (skiing and shooting), triathlon (running, biking, and swimming), and so forth, but even in these events competitors know exactly what they are getting into and train themselves specially for these events.

My proposal: an event consisting of 3-7 different disciplines, which are randomly selected each year from the pool of disciplines typically used in compound events, and which are kept totally secret until the day of the competition. The event would be designed to be completed in a reasonable (if somewhat random) length of time (say not more than 12 hours), and would not require significant special preperation thus allowing teams to economically be prepared for disciplines that may not be included (sure, some teams may spend ridiculous amounts on custom bicycles and whatnot, but they don't have to--historically teams with normal equipment have done comparably well with those who spend a lot of money).

To do well in this event an athlete must train in a wide variety of disciplines because s/he doesn't know what s/he will be called on to do. This would make it a good test of wide-ranging overall athletic ability (or at least make it interesting to watch and talk about). Naturally there would be no world records in this event, but getting the Gold in the X-Athlon would be an astounding achievement in itself, and such athletes would probably be well-prepared to do well in other more traditional events.

[edited to fix -athlon suffixes]