Here are pretty much all of the theme songs:

The Season One Theme Song:
http://youtube.com/watch?v=rjCMYQt0UBU

The Season Two & Three Theme Song:
http://youtube.com/watch?v=19jAJHLCiSs

The Season Four & Five Theme Song:
http://youtube.com/watch?v=9-OhM9lPOkE

The Season Seven Theme Song:
http://youtube.com/watch?v=O72HDaLHVRE

The Ending Theme Song:
http://youtube.com/watch?v=7tlABajJGCc

Did anybody watch them?!