The Complete Record Timeline/Summary (Communication + Updates) extension, shortly known as Timeline is now available for all version of VTiger 6. Previously it only supported VTiger 7 and above.
The extension is extremely beneficial to quickly see any communication (emails, calls, comments) as well as record updates. It rolls up the information from 3 relationship level deeps, meaning if you are viewing organization timeline, you will see any information related to organization (emails, updates, comments) as well as any information related to organizations’ tickets/opportunities (or any other modules), meaning that you would see any comments added to the ticket/organization while looking at the organization timeline.
More information about the extension can be found on the product page here.