I swear, they should have a "my friends paid $135 to see Cream but wouldn't shell out $20 to see The Decemberists with me" singles section at these concerts so kindred spirits can hang out together.  I hate going to concerts solo, because I never know how to meet people (even along people standing right next to me, perhaps even a little too close) and never know what to do with my hands (Pockets?  Lame.  Crossed?  Aloof and defensive.  Holding drink?  Difficult if the crowd gets rowdy).  When I went to a Summerstage concert alone, I actually brought my iPod, my theory being that if I was going to be a lonely alienated loser, I might as well keep myself entertained.
So you figure out how to rock out solo at a Decemberists concert, you share that info, y'hear?