Which Aircraft Models need a Tripod Jack for tail support at airport?
Tripods are mostly found in cargo aircraft (and combis) as the cg shift is severe there (particularly for front loading). A good example is the Boeing 747s. Also used in DC10/MD11s used as freighters. 



Image from reddit.com

Some 747-400 combis also use these, though it is mainly for cargo loading.



Photo: Je89 W. / Source: PlanePictures.Net

Some passenger airliners are prone to tipping (737-900 comes to mind) and are usually supported by a pole rather than by a tail stand (same procedure is used in a KC-135 tanker too). For example, a Boeing 737-932ER with tail support.



Image from airliners.net

The tail supports are not strictly necessary and the loading can be carried out sequentially (from front to back) for safe operation, but are used as a  precaution. In some aircraft (like ATR-72 and Saab 340, called pogo sticks) small tubings are attached to the rear fuselage to prevent tipping over when loading/unloading.



Image from theflyingengineer.com

The nose can be tethered to prevent tipping during loading/unloading as done in this Korean Air 747F



Image from koreanair.com