I am 13 and wanting to get a summer job next year an was wondering which programming language should I learn to get a fair amount of customers. Thanks!
Just stick with C++. If you already know the basics learn some web based packages to augment your skills.
Keep in mind though that there won't be many companies willing to pay much for a 13 year old beginner with no degree. Plus you'll be competing with college students and teachers who also have to summer off 8^(. But you can always do some free lance work. Maybe set up some websites or write an inventory tracker for local small businesses? Get you coding practice in and spread the word that you're available to help people out. Good Luck!