Powerhouse Brewery (Dublin)-rumored to be one of the better ones in regular production, especially on draft. Had it in bottle, will be able to confirm/deny the draft in about 4 weeks.
Harpoon Brewery (Mass.) did one as part of their 100 Barrel series that I thought was excellent, especially considering I haven’t liked much from them in years.
Marstons (UK) used to do one but I haven’t seen it over here in years, so can’t say for sure if it still exists.
Burnside Brewing Oyster Strong Ale
Burnside Oyster Strong Ale was brewed with 18 gallons of Hama Hama oyster liquor, and 4 pounds of lemon peel. This unique offering has a complex malt flavor profile and deep garnet color. Aged for 6 months, this is as limited and special a release as they come.
Harpoon Oyster Stout combines Boston’s Harpoon Brewery with the Island Creek Oysters from my hometown of Duxbury, MA. Not sure if the age verification screws up the link, but their Oyster Stout has been released twice now as part of their 100 Barrel Series, and could well become an annual edition.