Grab a Steigl beer and sit on the banks of the Salzach river, the main river in Salzburg. You can buy a normal Steigl in the Billa across the street from the bridge side that is not the side of Mirabellplatz. Be sure to grab a few flavors, Steigl makes a Lemon Radler and a Rasberry Radler (the Rasberry Radler is to die for!) Or you can go to the Steigl Brewery and see the whole production and drink some beer at the end! http://www.austrianbeer.co.uk/?Stiegl_Beer
Mozart Balls are a trademark of Salzburg, so make sure you grab one before you leave! Save up your money for a real one from the stores that sell the blue and silver wrappers (not the red and gold ones sold in the grocery stores/some of the tourist shops). You find the real ones down by the Gatriedegasse they will have shops fully dedicated to real Mozart Balls. They have marzipan inside! :) (I accidently smooshed mine before I could eat it by the banks of the Salzach).
Want some delicious salads or tea? You have to check out the Afro Cafe! This place is so fun with it's bright colors, outside seating, awesome fresh tea leaves tea with fun timers, and yum yum salads! It is just one of those places you have to go to just try it out! :)
My favorite cafe? Hands down the Modern Art Museum that is on top of the hill behind downtown Salzburg. You can see it from far away up by the fortress, and if you don't want to hike up (which it is a beautiful hike!) you can take the lift up the mountain for 2 Euros. :) Once you get into the museum head up another floor and go to the cafe. Head for a window seat or one of the couches. It is especially priceless during the winter looking over Salzburg outside the full size windows! The beautiful reds and crisp flowers with delicious apfel strudel (apple strudel) and famous Austrian Sachetorte (you better try both!) and a cafe latte or cappuccino plus good company makes for a perfect day! I remember sneaking up there whenever I could. :)
Last but not least make sure you get some Schnitzel with a berry jam that is like cranberries on top or a fresh squeezed lemon. You find the best one at Salzburg College's cook's table where Brigita works her magic, but other than that you can find a good one pretty much anywhere in town. :)