Program that outputs a program that outputs a program ... that outputs "Hello!"

Golfscript 39 14

~'Hello!'{`}@*

Example:

Assuming that n=4 and our program is P, these are the steps:

1. Run P with parameter 4. The output is "\"\\\"\\\\\\\"Hello!\\\\\\\"\\\"\"" (P₁)

2. Running P₁ outputs "\"\\\"Hello!\\\"\"" (P₂)

3. Running P₂ outputs "\"Hello!\"" (P₃)

4. Running P₃ outputs "Hello!"(P₄)

5. Running P₄ outputs Hello!. If you don't trust me, follow this link ☺.

Perl (45 36)

say"say q("x($m=<>),"Hello!",")"x$m         

Run with perl -M5.010 to use say.

For n=1, outputs say q(Hello!)
For n=2, outputs say q(say q(Hello!))
For n=3, outputs say q(say q(say q(Hello!)))
and so on.

JavaScript, 58 chars

function $(_){alert(_?$+'$('+--_+')':'Hello!')}$(prompt())