Minnows, night crawlers, and leeches are my top producers. Crawfish can be just like crack to fish. Peeled tails or in some cases whole. They can be a bit more expensive. It is really important to check the regs of where you are fishing as to what live bait you can use. In some waters crawfish and minnows are a no no.
Maui Jim covered just about everything, but I would like to add that using live bluegills can yield you some big fish. I have caught bass and catfish using this method. Although if I am targetting the cats, I usually use 'cut' bait (just the bluegill's head with the guts exposed). My biggest is a 30" catfish.
If you use bluegill that you caught in the lake you are fishing in, this is legal in Illinois.