The previous thoughts were very strong.  The Second Continental Congress' fundamental importance was that it was one of the first times that the colonists were acting like a real government, responsive to the needs of the nation.  The Congress braced for war, selecting Washington as the commander of troops.  They also ordered the printed Continentals, the first national currency of the new nation.  Additionally, the Congress began the process of committing itself to winning the military conflict with England, as opposed to seeking to find ways to avoid it.  There was a sense that the Second Continental Congress was beginning to give shape and definition to the new nation in one of its most intense hours fraught with peril.

The Second Continental Congress, presided over by John Hancock, consisted of delegates from the thirteen colonies. It occurred shortly after the Revolutionary War had started. A couple more notable figures who were delegates were Benjamin Franklin and Thomas Jefferson. Here are some major contributions:

• Military-Congress took control of the army outside Boston-George Washington became Commander in Chief of the Continental Army.
• Statements of Position-Olive Branch Petition and Declaration of the Causes and Necessity of Taking Up Arms.
• Financing the War-paper certificates were issued and money was borrowed from domestic and foreign sources. Money was a problem during the war because of deflation.
• Declaration of Independence

The Second Continental Congress met in Philadelphia, Pennsylvania.  It started meeting in May of 1775 and continued until the Articles of Confederation were ratified in 1781.

So, given those dates, you can imagine that it did quite a bit.  Perhaps its most famous action was to write and sign the Declaration of Independence.  This, of course, declared that the American colonies were independent from Great Britain.  After that, the main accomplishment of the Congress was to help get the colonies through the Revolutionary War successfully.  This meant that it had to raise money for armies and it had to, for example, get France to enter the war on the American side.

I should also mention that the Congress wrote and passed the US's first constitution -- the Articles of Confederation.