From Wikipedia

The Steelers have used black and gold as its colors since the 1950s. Originally, the team wore solid gold helmets and black jerseys. Unlike most other cities, the colors are currently also used by the Pittsburgh Pirates baseball team and the Pittsburgh Penguins hockey team, making it the official team colors of every professional sports team in the city.

The Steelers logo was then introduced in 1962, and is based on the "Steelmark", originally designed for U.S. Steel, by Cleveland, Ohio based Republic Steel, and now owned by AISI. (Does anybody else find this ironic?) It consists of the word "Steelers" surrounded by three astroids (hypocycloids of four cusps). The original meanings behind the astroids were, "Steel lightens your work, brightens your leisure and widens your world" and later the colors came to represent the ingredients of steel, the yellow representing coal; the orange, ore; and the blue, steel scrap. [1] While the "Steelmark" logo only contains the word "Steel", the Steelers were given special permission to add "-ers".

The Steelers are the only NFL team that puts their logo on only one side of the helmet (the right side). At first, it was a test to see how the logo appeared on their gold helmets, but its popularity led the team to leave it that way permanently. (It's also been rumored the team's longtime equipment manager, Jack Hart, wasn't happy with slapping the logo on so many helmets and refused to do both sides). [2][3] A year after introducing the logo, they switched to black helmets to make it stand out more.

The Steelers started to use their current uniform design in the late 1960s. The design consists of gold pants and either black jerseys or white jerseys. The helmet is solid black with a gold central stripe and small white uniform numbers on the forehead. Since 1997, each player has worn a Steelers logo patch on left side of his jersey.

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One thing that is so awesome about the Steelers is how rich the team's history is. It's amazing how a football team is so closely tied with Pittsburgh's industry, heart and soul.

For more information on Steelers history, I highly recommend this DVD:
NFL Films - Pittsburgh Steelers - The Complete History

Pittsburgh Steelers Snack Helmet

Pittsburgh Steelers Helmet Mailbox