I love hearing a capella versions of familiar songs (even humorous, tongue-in-cheek ones of heavy metal and rap and such), but don’t really get a chance to see any groups. Any suggestions for where online (a group’s website, etc.) I can listen to such music (legally, please)? Thanks. 
The Edlos have some mp3s, as do The Bobs. You could also try searching for a cappella songs at mp3.com.
There are some good samples at the site for Da Vinci’s Notebook. You can check their tour schedule, too, they might be coming somewhere close enough for you to see them.