A newer post on knitting sports team hats by knitnscribble is here. Your team not included in this list? Read the article linked below.
New England Patriots
Boston Red Sox
Green Bay Packers
New York Yankees
For more information on how to create team logo charts and how to apply the chart to your knitting or crochet pattern read "Knit and crochet Patriots and Bruins hats or any team logo pattern" for links to free hat patterns.