there some plugins like this but if i were you, i do not use that kind of plugins. they cause cpu problems. use google analytics or addfreestats.com.
Statpress is pretty nice (http://wordpress.org/extend/plugins/statpress-reloaded/). Otherwise, why not use analytics?
I'm using the free version of SiteMeter. It gives some basic info, but in my opinion, not enough. I'm actually looking for some good, free, client side stat script too.