I like the bold, colourful style used in US sports team logos, and struck upon the idea of creating a badge that would represent a whole city/state by combining the logos of teams from that area.
The teams used are primarily from the 'Big 4' leagues in US/Canada, and sometimes the soccer league:
NFL - National Football League
NHL - National Hockey League
NBA - National Basketball League
MLB - Major League Baseball
MLS - Major League Soccer
For each new logo I wanted to include at least three teams for it to feel like an effective conglomeration. I went with cities' teams if I could to keep them more localised, but expanded the design to a state if it meant I could incorporate more logos. For example, Milwaukee only has two teams but the state of Wisconsin has three, thus that is the combination I used.
Each team had to be represented in the design somehow, and in some cases having more logos to work with made this harder; I usually started by picking out the logo I felt was least compatible with the rest and deciding how to incorporate it. I often opted to use its colours by way of avoiding using the sometimes awkward imagery. A large amount of teams include the name of their city/state in the logo (or its initial), so a lot of the time I would use this as an identifier for each new badge.