As you all know, GO command signals the end of the batch of T-SQL statements

However in SQL Server 2005, it is also used to execute set of commands for a specified number of times

Consider that you want to create a table that should have hundred random integer values. You can the methods like the ones specified in http://beyondrelational.com/blogs/madhivanan/archive/2007/10/10/generating-random-numbers-part-ii.aspx or a while loop. 

You can also use GO command by specifying how many times it should run

create table #numbers(random_value int)
GO -- Signals the end of the batch

insert into #numbers(random_value) Select cast(100000*rand() as int)
GO 100 -- Signals that the above statement should run for 100 times

select random_value from #numbers

Now the table would have 100 random interger values

Here is Fun With Go