Do you mean visitor stats. Not sure what you mean by tracker, and this could be why you've not received any responses.
yes as in tracks visitors. The more high tech the better (refering sites, SE, paths, etc) Sorry for being so vague.
No problem. I just blogged about stats applications in my blog. Performancing Metrics is my fav at the moment and very easy to implement.
Instantly Also helps if you are using Adsense - helps you keep track of the clicks, which means you'll find any suspicious clicks from click fraud quickly. Read my blog entry (click the link in my sig) more info.
Could also use one that's easy to understand and install. Bahh! Ok just recommened me any that I can use which you can recommend. I would try everything anyway.
Wyla's right - put Statcounter in the footer - it's free and does all you'll probably need. Free at Statcounter.com