Most every summer neighborhood festival in Madison has good beer on tap, but yes, the Great Taste of the Midwest is the king-- it's just harder than snot to get tickets if you miss the day they go on sale. But man, if you get hold of one-- plan the entire day off, and bring a camera.
Quivey's Grove may hold their fest
again this fall.
I'd also strongly suggest the WORT block party, the earliest of the neighborhood festivals. Partly sponsored by the Madison Area Home Brewers
, which also put on the Great Taste, they always have a decent selection ("No Crap on Tap") of maybe a dozen brews over the course of the day, and is small enough to be comfortable. This year it's on May 17th. Admission is free, and there are good live bands, food, and various other vendors.
Just found this link of Madison Area Beer Festivals
, although most are not centered around beer. Probably should just be labeled Madison Area Festivals.
Anyone know if the Essen Haus is still holding a summer festival in their parking lot? Seemed like it was petering out last I attended about eight years ago.