Image Counter
There are several pre-designed download bars that can be used to show the number of downloads of Firefox there has been. It is simply a matter of copying the supplied code in to your site. You way want to change the URL used in the link to your own. I use my SpreadFirefox.com referrer link so the person gets the Firefox download page, and I know how many clicks there has been.
Alternative Image Counter
The above method of providing an image is not quite as great as a friend of mine would like, you can't use your own image. This can be got around by using a simple technique of overlapping two images.
So that is our two images, and once put together they look like this.
Now that will not quite work right in IE as it does not support transparent PNGS. You will need to get a copy of a PNG Fix script that will make IE recognize the alpha transparent PNGs. You will also need something like the code below to insert the script into your page (any where will do really).
<script type="text/javascript" src="http://yoursite.com/a-folder/pngfix.js"></script>
Creating the Alternative Image
You will need to put our own image URL in the above code
JavaScript
Did you know Firefox has been downloaded almost 500000000 times?
Yes the final method is to use JavaScript. This is as simple as putting the below two snippets of code in your page.
Place this where you want the number to appear. You can put some text inside it like I have just incase JavaScript is disabled.
<span id="firefox-downloads">almost 500000000</span>
Place this anywhere in your page after the above snippet
<script type="text/javascript" src="http://codefisher.net/firefox/download.js"></script>
Getting the download number via Script
If you like you can also add the download counter into something of your own you can get the download number from the following URLs. Unlike the Mozilla download feed for this, it only contains the numbers and nothing else. It is also kept ticking over at a rate made from the average change over the past two hours, the Mozilla feed only changes ever 5-15 minutes.
http://codefisher.org/firefox/download
Or if you want to get the rate at which it is changing per second (two hours average) use (numbers separated by ":")
http://codefisher.org/firefox/download?change=true