Slash the defense budget.
Enact single payer health care to gain efficiencies in health care delivery. Paying insurance companies 35% for what Medicare and Medicaid do for 2 - 4% is ridiculous. It would increase government spending, but you would have to raise taxes by less than individuals and businesses spend on insurance. The government's new found ability to negotiate with providers should also help slow the growth of Medicare and Medicaid.
Invest more in training doctors and nurses so that wages in those fields will be lowered in the future.
Raise the cap on SS taxes to $250k. That alone will create a surplus in SS. Use the surplus to increase payments under SS.
Means test half of SS benefits. No sense paying those with more than adequate incomes to collect SS. For those who are truly wealthy -- say income of over $240k/yr. in retirement, no SS benefits in those years when they have that sort of income.
End agricultural subsidies in all cases, or at least for large farmers.
End corporate welfare style programs.
In a graduated, but fairly short time horizon -- say five years -- increase gasoline taxes by $2/gal. Spurs alternative energy development to get us off of Middle Eastern oil, slows global climate change, and creates revenue.
End the two un-winnable wars of choice in the Middle East ASAP.
Eliminate preferential treatment of capital gains and dividends over $5 or $10k per person.