Maybe he would've prevented 9/11. There was a document "Osama bin Laden Determined to Strike in the United States" that Bush didn't read. Bush was incompetent. Gore would've read that document right away and taken the appropriate steps to protect our country. Even if 9/11 still happened Gore would've handled the situation much better. We would have never gone to war in Iraq.
More progress would've been made against global warming. And we'd probably have achieved not just more affordable health care but a single-payer system. If not during his presidency then under the next president.
2008 would've been a special year. We would've achieved the important milestone of electing the first Jewish president, Gore's VP Joe Lieberman. He may be a bit on the conservative side of the Democratic Party but he would've played a key role in helping to bring about peaceful relations between Israel and Palestine. They would have signed a peace treaty and would be recognized by the whole world as independent states and would be trading partners.
This year? Who knows. With all that Democratic Party win the Republicans would have to rethink their strategy and their entire platform. Maybe a reasonable Republican would be elected, maybe in this alternate timeline he (or she) is good enough for me to vote for.
Even though the wars would have been unavoidable, he would have most certainly controlled the pollution and would have pushed for more renewable power generation and the use of ecofriendly and highly efficient products. If there was a lesser dependence on oil, certainly these wars wouldn't have at least lasted so long.