You definitely can't take code you wrote for other people, but attacking similar problems is usually fair game. Even better, I've seen a few instances where a f

You definitely can't take code you wrote for other people, but attacking similar problems is usually fair game. Even better, I've seen a few instances where a freelancer agreed to tackle something for a reduced rate with the express agreement that they would also be re-using, reselling that portion of their work. This struck me as very clever as it was a way to keep cash flow up by continuing to freelance, but also to get that crucial first paying customer who can help guide you in building a product.