Primes (65 chars) for(n=1;n++<100;){for(i=1;i++<n-1;)n%i?0:i=n;n%i||console.log(n)}
Regex Primes (65 chars) for(i=1;i++<100;)/^(11+)\1+$/.test("1".repeat(i))||console.log(i)
FizzBuzz (64 chars) for(i=0;i++<100;)console.log((i%3?'':'Fizz')+(i%5?'':'Buzz')||i)