Because I do a lot of solo travel for my job, I attend a fair amount of baseball games by myself. Grab a scorecard and a beer and don't be afraid to chit-chat with those around you. It's not as fun as sharing the game with people you know, but definitely better than sitting at home and watching on TV. As an aside, if you are solo and watching a road game be courteous. I was in Denver watching the Brewers sweep the Rockies (in 2004 I think) and I got a little loud in front of some demoralized Rockies fans and they just about threw me out.