First of all, since we are in the worst financial crisis since the Great Depression, I think leading the nation and world to economic recovery would certainly put him on a near-Rooseveltian level.

FDR: In office
March 4, 1933 – April 12, 1945

See stock market [long term]:
http://finance.yahoo.com/echarts?s=^DJI#symbol=^DJI;range=my

Today is nothing like the great depression. Could we enter something like the great depression? It's possible. But we currently are not even in a recession. The stock market is down- down a lot. So it's a reasonable guess will be in a recession next year. but it's not a given that we will be in strong/long recession.

Recession: Definition
"A period of general economic decline; specifically, a decline in GDP for two or more consecutive quarters."

"So how can we tell the difference between a recession and a depression? A good rule of thumb for determining the difference between a recession and a depression is to look at the changes in GNP. A depression is any economic downturn where real GDP declines by more than 10 percent. A recession is an economic downturn that is less severe.

By this yardstick, the last depression in the United States was from May 1937 to June 1938, where real GDP declined by 18.2 percent. If we use this method then the Great Depression of the 1930s can be seen as two separate events: an incredibly severe depression lasting from August 1929 to March 1933 where real GDP declined by almost 33 percent, a period of recovery, then another less severe depression of 1937-38. The United States hasn’t had anything even close to a depression in the post-war period. The worst recession in the last 60 years was from November 1973 to March 1975, where real GDP fell by 4.9 percent. "
http://economics.about.com/cs/businesscycles/a/depressions_2.htm

November 11, 2008 (Close of Day)
Inflation % 4.94
GDP Growth % -0.25
Unemployment % 6.50
Gold $/oz 733.75
Oil $/bbl 59.33
Prime % 4.00
http://www.forecasts.org/gdp.htm

Now, if Obama raises taxes significantly we might get a severe recession or even Depression.

"Since the planet is experiencing climate change and America is heavily dependent on foreign energy, to the detriment of its national security, I would consider converting America to clean, domestic energy would qualify him for greatness."

You mean that since the planet has been cooling for last 7 years or has had flat to declining global temperatures for last 10 years?
As you know, if you want to keep the lights on, and if you want energy from a source that does not involve emission of CO2, you NEED to use nuclear power. No one thinks you can do this on solar and wind. Hopeful- to the point of delusional- puts wind and solar at getting about 10% of our needs within a decade or two.

I don't think Obama is going to push for more Nuclear power plants- and I wouldn't be to surprised if he kills the ones being ramped up.

"Since there are 70m Americans without health insurance, and since millions who do have health insurance are often denied, or given what amounts to a coupon and are stuck with 90% of the bill, fixing health care in this country would absolutely qualify him for greatness."

Nope. Not greatness.

"Since the vast majority of the planet has viewed America as the next Nazi Germany for the last 5 years, re-engaging us with the rest of the planet and solving some of the world's more intractable political problems would qualify him for greatness."

Sure. But be specific.

"What incoming presidents have had more challenges than Obama? George Washington, Abe Lincoln, FDR. That's about it. All three of them are considered great presidents."

Two of these presidents were involved in a major war. One was the commander of a war which was won.

Let us hope that Obama wouldn't be involved in a major war.
Bush wasn't. True that Bush was in office, when a enemy was successful in murdering a lot of Americans on American soil [a rare event in American history], but Iraq and Afghanistan were more police actions then what one would call a major war.