Do not use these faucets more than once to get an idea of how the coin works. I used to many of them and now I have 0.05BTC on my wallet which I cannot transfer: the transfer fees are HIGHER than those 0.05BTC shared among a zillion microtransactions. Bitcoin gives you a penalty if you try to add so much information to the blockchain just to make a small transaction.
As for your question, they most likely show that to let you know that they are actually giving you a bit more which can end up making an additional satoshi if you use their faucet enough times.
Two and a half years ago after I found news about the robbery at MtGox. I dismissed Bitcoins as something too unsecure to give it any attention at all. Then this year on March they came back to my mind. I thought "Let's see what happened with these digital coins I found a couple years ago". I wish I had bought in 2011...