Major League Baseball
A few examples of what you can ask Wolfram|Alpha about:
Teams
get information about an MLB team
compare several teams
get information about a division
request a team statistic
compare teams by a specified statistic
get historical team stats
rank MLB teams by specified criteria
Players
get stats for an MLB player
get historical player statistics
compare player stats
rank MLB players by specified criteria
find MLB players meeting specified criteria
get salary information about MLB players
find awards for MLB players