For one of the exercises in my training materials, I put together an exercise using the random number function. It's a times table document that regenerates itself every time you open it.
Click this image to see a larger version. The first number in each multiplication is fixed, and the second is random.
Here's the file if you just want to download it.
I did it by entering 1 - 12 in three columns. I just typed 1 in the top cell, then dragged the small lower-right-corner of the cell down to create a series of 1-12.
I did the same with the x for the multiplication sign.
And I put this formula in each cell where I wanted a random number between 1 and 12 to come up.
The document regenerates with different multiplication questions in different order each time you open it, so students can't remember which answers were where. Print the document to PDF if you want to preserve it in a particular way.
I've created another version here, a random number between 1 and 25, multiplied by another random number between 1 and 25.
For other ideas, see Plugged In Home School for a tip on making a word find puzzle.