My Old Kentucky Homebrew just opened up at 1437 Story Avenue, and I highly recommend checking it out. I went by for the first time last night (because I'm planning on starting my first batch of beer next week), and I was fairly impressed.
The owner, Paul Young, is an extremely nice guy and he has structured the hours such that its easy to come by after work. If my memory serves me, they'll be open Tuesday-Sunday, and the weekday hours will be 10-7.
Also, he'll often be conducting basic homebrewing classes on Thursdays.
The store appears to be fairly well stocked, and he has even more merchandise coming in soon.
He'll also be participating in the Trolley Hop this month, so if you're out for that make sure to stop by.
Additionally, LAGERS (Louisville's homebrewing society) members get a 10% discount.
If you already homebrew, or you're interested and would like to find out more about it, you should pay him a visit soon.