Katz's Deli & Bar is located at 618 West 6th Street in Austin, Texas at the corner of 6th and Rio Grande. It is a kosher restaurant and is open 24 hours a day. A typical breakfast for me there would consist of challa french toast with a side of either beef bacon or a potato pancake. Katz's is also the only place in Austin I know of that you can get an egg cream or rice pudding.
Katz's is located further down 6th street than the majority of the bars and as such has become a pretty common late-night destination for club-goers after the bars close at 2 A.M. The clientele you will see on any given night is a crossection of the people who live and work in Austin. Slumming celebrities, dirty hippies, and Japanese businessmen will all be crammed next to one another. Word of warning: Avoid this place like the plague during SXSW as it's perceived "trendiness" makes it impossible to get a table.
The waitstaff is friendly and leans towards the philosophy major dropout side, as do most of the "old Austin" eateries (i.e. Kerbey Lane, Magnolia Cafe, Romeo's, etc).
Owner and proprietor Marc Katz is a bit of a local personality. He is instantly recognizable from his myriad appearances in television commercials for the restaurant and is not shy about repeating the catch phrase from his commercials: "I gotta tell ya, Katz's never closes!" This is sometimes rendered on Katz's merchandise (t-shirt, ballcaps, keychains, etc, all available at the gift shop) as simply "Katz's never Kloses!"
All in all Katz's is a laid-back and unpretentious place to nosh.
Note to Austin readers: if you haven't been to Katz's in the last year or two, try it again. They have made a number of changes to the restaurant that brings back the quality they lost in the late 90s.