Multiple custom field sets in one contact tab (not the main one)?
Unfortunately there is no way to show all the custom fields in a single tab. However you can show all the custom fields on the Summary tab for that you will need to update each custom group to use 'Inline' for 'Display Style'. There is an extension released for 5.5 which developed by Coleman called 'CONTACT LAYOUT EDITOR' which allows you to rearrange the contact summary screen, Move the most important information to the top, Remove unnecessary stuff from the screen. 

HTH

Pradeep