Please give me some good riddles/brain teasers?!

Please give me some good riddles/brain teasers?

Please please please give me some good riddles! lol

Something like the following:-

QUESTION:
Cowboy Blake rides into town on Thursday. He checks into the local saloon and stays 3 full nights and 3 full days, about 72 hours. However, when he leaves, he leaves on the same Thursday. How?

ANSWER:
Thursday is the name of his horse!

I can run but never walk and I have a mouth but never eat. What am I?


A river.