From http://wiki.vtiger.com/archives

Tooltip Management

About

Tooltip manager is an utility provided inside vtiger that gives you the ability to view detailed information about a records when you hover over it in the listview. Using tooltip manager, you can relate a field to multiple fields within a module and see them all in a tooltip (ballooned text), when you hover over the field. This means lesser trips to detailview and access to more data.

How does it work

Firstly you need to relate some fields. Say you relate the First Name field of Contacts module to Email, Reports To, Assistant, Yahoo ID, Assistant Phone, Do Not Call, Email Opt Out, Assigned To, Reference, Created Time, Support Start Date, Other City and Mailing State fields. After relating, when you hover over the first name field (say Elizabeth Brown), then you would get the resultant in the list view of the Contacts modules.

How to use it

To enable the Tooltip Manager, do the steps following :

• Go to Settings >> Module Manager.

• In the Module Manager page. Click on the module setting icon found on the right corner of the each module for which you want to add a Tooltip.

Alternate Method: Select a module which you want to add a Tooltip. Click on the module Settings icon 
in that module page to go to tooltip management

• It opens a setting page. Click on Tooltip Management link, which takes you to Tooltip Management page.

• Here you get a Select Field dropdown for the selected module.

• Once you select a field from the Select Field dropdown, it gives you a list of fields that can be related.

For example, if you select Account name in Account, it will show the field that can be attached to 
Account name like Account no, phone, Website, Other Phone, Rating etc..

• Select the fields that you want to relate to the field.

• Click on Save to update the Settings.

• Once you save the settings, you will get a tooltip information for the field in listview.