Tooltips in everviz data visuzlations are great for adding extra information in bit-sized chunks.
Did you know the tooltip also supports clickable links?
Hover your mouse pointer over Alaska (AK) to see the clickable link in the tooltip:
The link itself is in a column, linked to point.extra, and looks like:
<a target="_base" href="www.everviz.com">everviz main page</a>
Want more details on how to do this?
This everviz knowledge base article shows you how to add clickable links to the tooltip.