Multiply it by a large factor and divide:

for my $n (0..100) {
   $n /= 100;

   # do something with a number between 0.00 and 1.00 
}
[download]

or, for something more arbitrary:

for my $n (437 .. 1287) {
   $n /= 1000;

   # do something with a number between .437 and 1.287
}
[download]

update: the more i read the question, the less certain i am i know what you mean... hope this helps, though...

[ ar0n ]