Beer batter or other? I prefer anything other than beer batter, but if you like beer batter I recommend Edgewater Lounge at Bryn Mawr and Ashland. All-you-can-eat and they have a great beer selection. Is this a lenten thing or are you a displaced Wisconsinite? :p
The Rail isn't bad- all you can eat for $9.99 or something. I know Will's Northwoods Inn has one but I've never tried it. Edgewater Lounge has been hit or miss for me in the past but definitely worth a try and a cool atmosphere.
St. Ferdinand Parish hosts the 'FISH FRY' every Friday during Lent. 3131 N. Mason, Chicago, 60634. 4:30 - 7:30 pm Carry out & drive thru service is available. Orders can be placed starting at 4:00 pm at 773-622-3022!
The Irish American Heritage Center on Knox has all-you-can-eat fish fry during Lent on Friday nights - the rest of the year, it's single order. Their building is beautiful and there's a lot of other stuff going on there - dance, music, art - worth checking out.
Definitely try St. Ferdinand's! Not an "all-u-can-eat" but very good size portions, with all the sides! Weekly theme night with entertainment for the whole family!! But above all, the fellowship is what makes it so popular! Nothing like being a part of the true meaning of the Lental season!!