If you want to give your users the possibility to promote their profile, for example: on their personal website, then you can provide your user a simple html code snippet which they can place on their own website.
You can create a HTML block widget and place it on their profile page. It looks something like this:
<div style="font-size:14px; text-align:left; font-weight:normal; padding: 15px; margin:0; background:#ECDFBF;">
<center>
Profile Promotion!<br><br>
<img src="HERE-YOUR-URL-TO-THE-SITEICON">
<br><br>
Use this html code on your website:
<br><br>
<font size="1">
<p id="site_profile"></p>
<script>document.getElementById("site_profile").innerHTML = "<a href=\"" + window.location.href +"?ref=promo\"><img src=\"HERE-YOUR-URL-TO-THE-SITEICON\"></a>";</script>
</font>
</center>
</div>
REMARK:
1. change the HERE-YOUR-URL-TO-THE-SITEICON into the full path to the icon.
2. the part "?ref=promo" means that you can check which users have place the html code on their website. You can check this in your server log files.