SPCoding School

This is actually a puzzle: Two people want to know who is richer without telling each other (and no third part) how much richness they have. How can they do so? What if, instead of two people we had three or more?

Here is another puzzle-like example problem, discussed in another IT School:

Let x_1, x_2 be two numbers drawn from a certain distribution and written in two slips of paper. A person may look at one of the slips and decide whether the number is the largest of the two.

Of course he can be right with probability one-half. However, it is very surprising that there is an strategy for which he is right with probability strictly greater than half. What is this strategy?

The problem is whether this generalizes for more numbers (x_1, x_2, ....)