There are so called "faucets", API endpoints that send you ether on the testnet (called morden).
I created a CLI script to make this easier for you. Just pass in your testnet wallet address and et voila: ether gets sent to you. 

p.s. I am in the process of creating a own faucet for this one. The public ones turn out to change in quality and availability. 

[ethrain cli script][1]


  [1]: https://github.com/sebs/ethrain