George Michael, 2007, in Madison Square Garden, New York.
Best concert I have ever been to. Great singer and performer, amazing show even though it's a relatively small venue for such a large act.
The best thing was that at least 50% of the audience was most definitely gay. The reason why this was awesome was, not as you might expect (<_<) that it created the an awesome atmosphere. Everyone who was there were there because they wanted to hear George sing, to see him perform. There was a group of gay men sitting next to us, and they were incredibly considerate. When one of the guys started getting worked up (took off his shirt and began dancing around) his friend got him to calm down, out of respect for us.
Best concert ever, definitely made me a fan of George Michael's music.