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Also, go to Barton Springs for what will be a well-needed dip in some frigid water!

hooray for Barton Springs!
Go to Chilito and Taco Deli.. breakfast tacos, lunch tacos, anytime, all the time tacos! I love Austin.

Ditto Pappadeaux for seafood, I ate there last night actually.

You can get some great carribean food at Habana Calle 6. (Right in the heart of downtown Austin, on 6th street.) I recommend the Lechon asado.

An Austin must is you have to go to one of the Baby Acapulco restaurants and have a purple margarita. Theres a 2 purple limit, so you get the idea.
The Baby A's down south is about a quarter mile from Barton Springs so you can go take a dip or rent out a canoe and take it out on town lake.

I could go on all day so I'll cut myself short instead, have a great time, I love this city!

-taco express does a gospel brunch/hippie church on sundays, live music and a crowd, 12 - 2pm, and they have great, cheap, tacos and horchata. it's on south lamar.
-east side cafe on manor road uses veggies from their own garden.
-a lot of people like salt lick or county line for bbq.
-torchy's and el chilito both have great tacos.
-thai passion is a good thai place downtown off congress. I also like titaya's on lamar.
-hut's hamburgers on 6th is a fun classic burger joint with shakes, fries, etc.
-some pricier/nicer options: jeffrey's has been around in austin forever. zoot and wink are good too.
-places for beer: dog and duck pub on guadalupe, opal divine's on 6th, draughthouse on burnet, and crown and anchor (good burgers) on san jacinto.
-daily juice has awesome juices and smoothies.
-for great pastries (austin doesn't have a lot of these, sadly), go to uppercrust bakery on burnet or sweetish hill on west 6th.

most of these are local restaurants or local chains :)

For Tacos, Torchy's is not the best option. Hit up the east side and Al Pastor on Riverside for awesome tacos, El Chilito on Barton Springs and Dawson (or Manor) is also decent. Tacodeli for breakfast tacos or Polvos for migas/chillaquilles.

Zoot is closed. Fabi and Rosi is now in that location, I have heard good things. Aquarelle, Uchi, Jezebel, all good upscale restaurants with interesting menus.

Amy's Ice Creams is the best way to beat the heat. My favorite is Mexican Vanilla but I enjoy their "spiked" ice creams like "White Lightening", "Black Velvet", and "Guiness" when they are in rotation. They have several locations throughout Austin so you're bound to pass by one.

The Whole Foods Flagship Store is downtown at 6th and Lamar. They have an incredible food court with an array of ethnic, vegan, and vegetarian selections if you are looking for something on the go. By the way, Amy's is just down the street.

I agree with all the TexMex suggestions. Don't forget to try a Mexican Martini. I rarely drink so I can't tell a good MM from a bad MM. Any suggestions for a good MM from the other readers?

For interior Mexican food, go to Fonda San Miguel's Sunday Brunch so you can taste a variety of dishes without having to order separate entrees.

If you're up late (or early), stop by Magnolia Cafe. They're open 24/7 and serve just about everything - breakfast, TexMex, burgers, etc.