http://www.louisvillehotbytes.com/
This link is a very through, very in-depth guide to many places to eat in Louisville. The site is maintained by Robin Garr, a local food critic. The site rates local restaurants on a 1-100 scale and gives price range and contact information. Louisville has a lot of local/unique restaurants that offer very good food.
http://www.louisvilleoriginals.com/
This link contains a lot of information about more expensive, local restaurants. If you have a more refined palate or you enjoy more upscale dining, you might want to check out this list. Be warned though, many places on this list are in the higher price range ($30+ per person). Below is my recommendation for more upscale dining in Louisville (most require reservations).
Jack Fry's - 1007 Bardstown Road (502) 452-9244
610 Magnolia - 610 Magnolia Ave (502) 636-0783
Le Relais - 2817 Taylorsville Rd (502) 451-9020
Corbett's - 5050 Norton Healthcare Boulevard (502) 327-5058
Porcini - 2730 Frankfort Ave (502) 894-8686
Asiatique - 1767 Bardstown Rd. (502) 451-2749
Café Metro - 1700 Bardstown Rd. (502) 458-4830
Equus/Jack's Bar - 122 Sears ave (502) 897-9721
Park Place on Main - 401 E Main St (502) 515-0172
English Grill - 335 West Broadway (502) 583-1234
Havana Rumba - 4115 Oechsli Ave. (502) 897-1959
Stevens & Stevens Deli - 1114 Bardstown Road (502) 584-3354
The Irish Rover - 2319 Frankfort Ave. (502) 899-3544
Del Friscos - 4107 Oechsli Ave (502) 897-7077
Pats Steakhouse - 2437 Brownsboro Rd (502) 893-2062
The Oakroom - 500 Fourth Street (502) 807-3463
Below is a list for those on a more modest budget (I fall in this group). You don't need a reservation for any of these an a meal + drinks will run you $10-25 per person depending on what you order. None of them will break the bank and all have great food IMO. These are some of my favorite places to eat out in Louisville and I highly recommend each of them.
Cumberland Brews - 1576 Bardstown Rd. (502) 458-8727
Great microbrew with great food. I highly recommend the Bison burger or Chicken Cordon Blue sandwitch. Also, they serve Mead, femented honey, which is expensive (8.50 a pint) but delicious. The nut Brown Ale is also very good. Very unqiue, hole-in-the-wall type of place.
Brendan's Restaurant & Pub - 3921 Shelbyville Rd (502) 895-1212
http://www.brendanslouisville.com/
Lot of beer choices (5 dollar sampler is great) and outstanding food. Fish and Chip is awesome. Great atmosphere, especially for the 30-50 crowd. You get a lot of food for your money.
Cafe Mimosa - 1543 Bardstown Rd (502) 458-2233
http://www.cafemimosatogo.com/
If you want some Vitnamese/Japanese/Chinese, I'd hit up Mimosa. You get a lot of food for your money. The Vitnamese Curry and Rice in a Pot are both awesome, but the sushi was mediocre though. Great place to eat if you like Asian cuisine.
Homemade Pie and Ice Cream Kitchen - Multiple locations around town
http://www.piekitchen.com/
Pretty much the best place in Louisville to get a desert. Great local chain and one of my favorite places to stop when I get a sweet tooth. Like the name says, the serve homemade pie and ice cream.
YOU MUST GO HERE WHEN YOU ARE IN TOWN.
Wick's Pizza Parlor and Pub - Multiple locations around town.
http://www.wickspizza.com/flash.htm
Local pizza joint that is a bit on the pricey side. Despite the cost, the pizza is excellent and some of the best in town IMO. I highly recommend the Chicken, Bacon, Ranch pizza or the mighty meaty wick. Good beer selection and the bar side has booth TVs to watch games (Bardstown location). Very snazzy place to grab a bit to eat.
Bluegrass Brewing Co - Downtown or Saint Matthew's area
http://www.bluegrassbrew.com/
Great microbrew with a lot on the menu. Summer Wheat Ale is outstanding in my book and ladies will like the raspberry Mead guarenteed. If you like bourbon, you might want to try the Bourbon Barrel Stout. Built-your-own pizza is an excellent choice as are the burgers. Great place to catch a game.
Mark's Feed Store - Multiple locations
http://www.marksfeedstore.com/
Very good BBQ that is pretty cheap (Not as good as the BBQ in Memphis but it is pretty good). Pulled pork and honey wings are excellent. If you like BBQ and you don't have a lot to spend, Mark's is a must eat place.
Buckhead's Mountain Grill across the river in Jeffersonville, IN
http://www.eatatbuckheads.com/locations/
Local chain of restaurants based here in Louisville. They serve a variety of food on their menu, from steak to Mexican to wings. The one in Jeffersonville has outdoor seating and is right on the river. Nice view of the Louisville skyline and a great place to eat and the food is good.
The Back Door - 1250 Bardstown Road
http://thebackdoorlouisville.com/
Let's be honest about two things. The Back Door is a typical bar (pool and arcade games in the back with bar area up front). It isn't fancy, it isn't unique, and it isn't some special bar. However, it does have excellent food (fish sandwich and chicken wings are great), it is one of the cheapest places to get drinks in town, and it doesn't have a bad/rough-n-tumble type of crowd. If you are looking to get a bit tipsy before going out on the town, I'd stop by the Back Door first (particularly if you are going to $th Street Live....they will literally rape your wallet on drinks).
Frankfort Avenue Beer Depot - 3204 Frankfort Ave
Great pulled pork sandwich, the beer is cheap, the place has a very casual atmosphere, AND they have games (putt-putt, pool, cornhole). Very chill place and a great place to visit when in town IMO.
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My recommendation is that if you are coming with a group of guys to at least hit up Wick's and Cumberland Brews.