Does my best friend have a lesbian crush on me?!?

It seems to me like she really does like you. The only way to know for certain is to tell her that you have something very important you wish to ask her in private, face to face. Tell her what you think she's doing and ask her if that is her true intention. Tell her what you truly think and feel about her, as well. You may not like the answers you receive, but it's better to know for certain than to lead her on or be led on by her. I wish you both the best, no matter what happens. :)