I found an svg file for the dolphins logo out on wikipedia and I just had to cut it. First I opened it in inkscape, and color separated things. Here is how it came out! I fixed the tail, it is missing a small white triangle. The files can be downloaded from mediafire.
http://www.mediafire.com/?wyyzmyjufjy
I think you can find other team logos on wikipedia, as well. I searched for miami dolphins svg file, and found this one.
http://en.wikipedia.org/wiki/Image:Miami_Dolphins_logo.svg
I also found the Florida gators and created a scal svg file for that.
http://en.wikipedia.org/wiki/Image:Florida_Gators_logo.svg
Here is the Dallas Cowboys:
http://en.wikipedia.org/wiki/Image:Dallas_Cowboys.svg
Atlanta Falcons
http://en.wikipedia.org/wiki/Image:Atlanta_Falcons_logo.svg
Washington Redskins
http://en.wikipedia.org/wiki/Image:Washington_Redskins_logo.svg
New York Giants
http://en.wikipedia.org/wiki/Image:New_York_Giants_logo.svg
I'm sure every team was in there. I looked for the Marlins baseball team logo, and found it, but it was a .png file. That will have to be bit traced, etc, so will be harder to use.
I checked another baseball team, Boston Red Sox, and there was an svg file for their logo.
http://en.wikipedia.org/wiki/Image:ALE-BOS-Logo.svg
Anyway, just wanted to share this souce for SVG files for your sports teams.
And don't forget BIG TEN MANIA FONT for all your big ten teams, like Penn State, Ohio State, etc.
Go Dolphins!