Ability to give away iOS application, usually for sale
No. Apple allows for only a very limited number of promo codes for the lifetime of an application (versions 1.0 - n.0). The exact number escapes me at the moment but somewhere around 100 comes to mind. You are allowed to have more beta testers, but that requires manual management of every user and isn't scalable should you need to go beyond your limit.

At the same time, there are pricing strategies you are free to implement, like free for the first 30 days, holiday and back-to-school sales, and the like.