After several positive reviews on various websites, I visited East End Brewing for the first time during their release of their 2009 Gratitude Barleywine. The brewery is located in a warehouse on the East End (well duh) and the only way you can tell it's a brewery is the small text on the door with the brewery's name.
This is the smallest micro brewery I've ever been to and quite honestly it's one of the best. The bartenders there are always very friendly and willing to hand out samples (not to mention give explanations of the styles of beer). While their year-round beers are great, I'm a big fan of their seasonal and/or one off beers. Their Smokestack Heritage Porter, Wheat Hop, and Snow Melt Winter Ale are great and very good examples of their respective styles.
If you thought Pittsburgh's only micro brew offerings were Iron and Penn Brewery, look a little closer and check out East End Brewing. Take it from this homebrewer, this is the best beer in the Pittsburgh area.