axenso

You can enable a tooltip that shows info about user/author when you rollover/click on related avatar.
Let’s speak clearly: if you are loooking for a plugin that enables the standard Gravatar hovercards, this is not the plugin right for you. Please look for another one.
When you rollover/click on an avatar (e.g. of a comment author), a tooltip popups and shows:
<ul>
<li>some additional links if the author is a registered user: e.g. to user post archive, to user external website, to user blog (if multisite)</li>
<li>some info from Gravatar if author is registered to that service: e.g. location, “about me” description, websites, other account pages (facebook, twitter….)</li>
</ul>
In plugin settings you can set up the javascript and css main options.
The plugin comes with some filter hooks, so you can customise the tooltip content at all.
The plugin uses <a href="http://craigsworks.com/projects/qtip2/" rel="nofollow ugc">qTip plugin for jQuery</a>.

Avatar Tooltip

To show a tooltip with info (member info and Gravatar profile) when you mouseover/click on an avatar.

Mehbub Rashid

Add tooltips next to Gravity Forms field labels very easily. Supports placements, themes, animations. 
Update: Now you can use shortcodes as tooltip content! 
Big Update: You can now use HTMLs in your tooltip and choose themes, animations, placements!
How to use:
<ul>
<li>Add your text to the “Tooltip Text” field while editing gravity forms fields.</li>
<li>Save changes and tooltips will appear next to label automatically in the form.</li>
</ul>

Tooltip for Gravity Forms

Work as expected!

Add tooltips next to Gravity Forms field labels very easily. Supports placements, themes, animations.

Avatar Tooltip vs Tooltip for Gravity Forms