What's a good way for me to start saving money fast?

I don't get allowance.I want to start my own business!Not like a real one that you need to have patented and all that good stuff!More like a business for a young kid, age 12-13 kinda job.I wanted to do something worth my while too.I'm saving up for a DSi, a nintendo game system.It's so cool.You can take pics and send messages!I want it so bad!I also want a kitten and a iphone too!If I get a small job that requires responsibility, my mom will probably let me get a cat or an iphone!YAY!