My oldest boy has a favorite shirt. Unfortunately it hasn't grow as he has. So after finally getting to see way too much of his belly button we performed a shirt-saving operation. I thought there might be a mom or two in need of the same thing.
First I cut off the sleeves right at the shoulder.
Then I just laid it on top of a larger sweatshirt(sorry another photo might have been nice here!) I pinned it in place and then just zig-zagged the edge all the way around.
Presto! Happy boy! And the shirt should be good for at least another year!