Lying.

So - we are having MAJOR issues right now with my 7 year old son and lying. It's constant and it's silly. I mean he is lying about crazy non-important stuff. What's up with that? I guess - I expect kids to lie to get out of trouble (not that that is OK, or acceptable - I just expect it), but for him to lie all the time about just weird stuff, what do I do? I mean he's lying to his friends, he's lying to his teachers, his sister, us - our friends! This is insane! I don't know what to do. Awhile back, I had caught him in a lie and made him eat soap. I told him that whenever he lied again, he would get the soap again. I've only had to use it on him one other time. Then last night I find out some more, so I make him stand in front of the bathroom mirror and hold the bar of soap in his mouth for 5 minutes. I guess my concern is - this isn't working. What do I do? There isn't one thing that I can take away from him to get my point across either. He doesn't watch TV on school nights, he plays his playstation 2, but not all that much. So if I were to take away either one of those - he'd be alright with it. SOooo...I just don't know. Any ideas?