Captain America's Shield

uses his Shield as a primary defensive and offensive piece of equipment for battle. His shield is made out of Vibranium.

Captain America: The First Avenger
Steve Rogers uses an ornamental version of the triangular shield during a musical tour promoting War Bonds, which he then uses in his first field mission. Rogers later acquires the familiar circular shield from Howard Stark. Rogers chooses the unadorned vibranium shield (actually a prototype) over several more advanced models based on the triangular shield. The Vibranium prototype shield proved to be the perfect weapon for Steve. As Captan America he accomplished amazing feats with it. Aside from bashing HYDRA soldiers and blocking incoming attacks, Rogers was able to throw it with near perfect aim and have it ricochet back to him.

Iron Man
Captain America’s shield appears 1 hr 25 min 23 sec into the movie at the point where Pepper Potts comes in on Tony trying to get out of his damaged armor; the shield is visible in the distance below Tony's right arm. According to a tie-in comic, Tony's father Howard Stark created the shield. Tony subsequently used the alloy of a prototype to create his armor.

Iron Man 2
Phil Coulson finds Captain America's shield in Tony's house.

The Avengers
Captain America's shield proved most effective in his confrontation with Thor as it absorbed the full impact from Mjolnir Thor's enchantmented hammer and causes a massive shock-wave to the surrounding forrest area. Steve uses the shield again in the battle with the Chitauri in New york to shield his teammates as well himself. Iron Man uses his Repulsors rays on Cap's shield to launch an effective counter strike attack on Chitauri unit. Cap then uses the shield to protect himself from a grenade blast that sends him hurtling out a window and to the street below unto the car roof. Because of the Shield structure Cap was able to curl himself and protect himself from receiving extensive injuries.

Trivia

 * In Captain America: The First Avenger, both Bucky and Falsworth wield the shield in addition to Steve. Bucky during his last stand on Zola's train, and Falsworth throws the shield to Steve in the final battle. In the comics, Barnes was Steve's successor as Captain America and Falsworth was the UK equivalent, Union Jack.