An email group I belong to has recently been discussing each other's blogs, trying to improve them. One of the things that comes up often in the discussions is the need to track traffic on our sites.
I'm going to come right out and say that I think the practice of displaying the number of hits directly on your site is passé. I know that people will disagree with me on this, but here's my reasoning: if your blog is popular, people can tell. You'll get a lot of comments, the blog will rank highly in Google for various keywords, you'll get a lot of Diggs, or whatever. And while you might think a certain number of hits is impressive, your audience will probably have a different opinion.
However, I think that it's vitally important to track the traffic on your website for your own purposes. How are you going to know which tactics work to increase traffic, and which don't? And luckily there are simple tools that let you do just that.
By far my favorite is Google Analytics. Anyone with a Google account can go to the Analytics site, sign in, and download the code for the tool. (I don't know if Google accounts are still invite only, but if you need an invite, let me know). Blogger layouts and Weebly layouts (and I'm sure others) have html modules that you can put anywhere on the page - plunk your code in there, and you're set! Later, you can sign in to Analytics and take a look at your stats. Analytics displays breakdowns of the information into various formats, including snazzy graphs and charts. In addition, you can get different chunks of code for different sites you own, and view all the statistics in one place.
I also have a Site Meter widget on my blog, way down at the bottom. I admit that if you click on it, you can see my statistics. However, in order to do so you'd have to know what Site Meter is, and you'd probably have a good reason for wanting to know my stats (i.e., to find out whether I'd be a good host for a blog book tour). The information is available, but only to people who need it. Site Meter is another good site for checking your own statistics, not quite as suited to my purposes as Analytics, but it does a decent job and I can check it easily from my blog anytime.
Another statistic tracker I've come across is StatCounter. I haven't used this one personally, but I've tried to click on StatCounter widgets on other people's sites and been taken to a page that requires a log in to see the statistics. I suggest that if you're going to offer a tracker as a widget on your site, make sure people can click on it to see the info without having to log in. If you don't want to use Site Meter or Analytics, StatCounter might work for you.
These are just the trackers I've had experience with. Let me know if you've had good/bad experiences with others!
In conclusion: if you're interested in increasing your traffic for fun or profit, don't delay in installing some sort of statistic tracker. But don't let just anyone see this information, unless you have a good reason.