OfFBeat is a free publication (both print and on-line) that tells everything that’s going on in the New Orleans music scene.
New Orleans Menu is a free site about the food scene in New Orleans, including many restaurant reviews.
Since you have only one day to see the city, I suggest sticking to a relatively small area and doing things that are unique to New Orleans. The city has its own cuisine, its own architecture, and its own music. Try to go to restaurants that feature creole food, and New Orleans specialties like mufulettas.
You can spend a lot of time wandering around the French Quarter. It’s like nothing else in the country. Bourbon Street is the most famous part of the Quarter, but it’s mostly bars and mediocre music. Royal Street is more interesting, in my opinion, especially because that’s where a lot of street musicians play. You can see some really good bands on Royal Street.
I agree with jaycat that most of the best clubs are on Frenchmen Street. It’s in a neighborhood just east of the French Quarter called “Fabourg Marigny.” You can check OffBeat for which bands will be playing on the day you’re there, or you can just walk down the street and see for yourself.
Some good places to eat in and around the French Quarter:
Mr. B’s - Gumbo Ya Ya, BBQ shrimp, Wood-grilled fish, Shrimp & grits. Don’t order both the Gumbo Ya Ya and the BBQ shrimp at the same meal - too rich.
Drago’s - Best known for char-broiled oysters. In the Central Business District just outside of the French Quarter. Sit at the bar for a free show - the process of grilling the oysters is pretty spectacular.
Muriel’s - Contemporary creole. Crawfish and goat cheese crepes. Pecan-crusted fish.
Cochon - Cajun. One of the best restaurants in New Orleans, in my opinion and in the opinion of many food critics. A bit outside of the French Quarter in the Warehouse District. Everything is house-made, including pickles and cured meats. Menu changes frequently. Reasonable prices, especially considering the high quality of the food.
Cochon Butcher - Next door to Cochon. Informal service, simpler menu. They make the best mufuletta in New Orleans, in my opinion. Smaller than the mufuletta at Central Grocery, but better quality ingredients and much less salty.