Actually I've just taken to this myself recently. I have no real method yet... just grab two beers and dump them together. The most interesting I found so far was a smoked porter with 1/3 of an apricot flavoured wheat ale.

Since you ask, it is pure heresy.

We have customers coming into the shop almost daily with wierd sounding blends. Here's three that I've tried recently (and enjoyed):

Raspberry cheesecake: 50/50 framboise and chocolate stout [use one of the sugary lambics like Lindemans, don't waste something good on an experiment like this]

Imperial Overload: 50/50 Imperial IPA and Imperial Stout. [you have to be careful with this one]

Dark Dog: Grab a pint glass and pour in a bottle of 90 Minute IPA, then drop a shot of World Wide Stout on top and watch it swirl...

I heard about these a couple days ago from a Rogue fan, but haven't tried 'em yet:
Snickers Bar: 50/50 blend of Rogue Chocolate Stout and Hazelnut Nectar

Old Crusty Bastard: 25/75 blend of Rogue Old Crustacean and Arrogant Bastard

Half Bud, half Miller High Life makes a great beige-and-tan.

I read somewhere that porters got their start this way. Bars would mix one kind of beer with another and the train porters loved it so much that the drink was named after them.

Guinness and Murphys half and Half: The Irishman's Delight
Discovered at the local pub when half way through filling a pitcher o' the staff we noticed a new Murphy's tap, which was promptly used to fill the last half.

So good it became a "menu" item.

Guinness and rasberry/strawberry mead is also very good.

The mead mixed 1/2 and 1/2 with a nice hard cider is up there on the tasty scale.

JC

It was a mix of a weak newer brew along with a "stale" ale that where mixed to create porters.

I prefer the Black and Blue or as I like to call them- lunar eclipse. Guiness over Blue Moon.

I can't say that I mix beers often other than the occasional black and tan or half and half. However, I do occasionally mix beer with liquor. The obvious ones here are Flaming Dr. Peppers and Sake Bombs. Liqueurs like schnapps and fruity things can also impart great taste to different beers.

BTW, yes, this is heresy. I only use bad beer for this. :)

I have not even thought of Labatt 50 and clamato, one of my restorative tonics. In Halifax in the '80s you would order "two and juice" which was two 8 oz glasses of beer and tomato juice. a Saturday noon drink.

Until about twenty years ago, beer stronger than about 2 % was banned in Iceland. When someone opened a pub where the big hit was light beer with a shot of the local aquavit (lovingly known as Black Death), they amended the law.

The true Black and Blue. Guiness and Atlantic Brewing's Blueberry Ale. Also good with Atlantic's Coal Porter in place of the Guiness.

Mmmmm...Maine be-ah. I'll be there in a few weeks for to load up. I think coal porter is one of the better names for beer.

I work at New Belgium Brewing Co. and we regularly blend our shift beers at the end of the day from the taps in our tasting room, keeps it interesting.
Some of our favs. are,
Sunshine Wheat and Trippel 50/50 called a Suntrip
Trippel and Biere de Mars 50/50 called a Trip to Mars

Last year we started a competition within the brewery based on tasting blended beers and guessing the types and percentages of each. The winner gets full access to all raw materials and equipment including advise and help from our Brewmaster, brewers, and cellar operators to produce any style of beer they so desire. The beer I made was actually a blend itself of a two year old sour beer from our wood cellar, peach juice and a strong golden ale I brewed with pale malt a bit of Carapils, unmalted wheat, and aged hops. So I would say that in my opinion it most definitely is not heresy and should be encouraged.

Hey Eric! That sounds like a good happy hour project. One blend I have been contemplating would be a decent biere de barde like Saison Dupont with just a bit (<10%) of blackcurrent lambic.

Your Lambic/Stout blend sounds a lot like something we used to do in college:

Yuengling Porter was only $4.50 a pitcher at Boxer's Cafe in Huntingdon PA. A bottle of Lindeman's Framboise added to the pitcher made for an interesting departure.

Oh yeah...and the 75 minute from JeffreyT on the goodbeershow.com

1/2 DFH 90 minute, 1/2 60 Minute

It's actually really good.

Did you know Dogfish did make a 75 as a one-off but didn't continue with it? I only know this from haunting beer advocate for adjectives to steal.

Donavan adds another blended beer.

samual adams cherry wheet and guiness. its deliciouso

Beauty and the Beast: 50/50 Guinness Kaliber and Milwaukee's Best Light