If you use the Sideview Utils app, either the 1.3.X version available on Splunkbase or the newer and better 2.0.10 free-for-internal-use version on sideviewapps.com, then you can use the HTML module from that app.
The app itself has extensive documentation about all the different modules that open up once you have Sideview Utils, and HTML is (as many others) quite simple to use.
<module name="HTML" >
<param name="html"><![CDATA[
<a href="http://google.com">go to google</a>
]]></param>
</module>
You can include dynamic pieces like $selectedSourcetype$ and it'll grab the values from upstream modules, and you can also refer to field values in the current search results, which means the HTML module is a great replacement for the SingleValue module.
But again, there's tons more docs and examples in the app itself.
http://sideviewapps.com/apps/sideview-utils/
