Are you able to access the web on your phone or some WAP type service? If not, you should sign up with 3 mobile
NBA Scores-
www.nba.com (Type this into the URL on ur phone, much improved service this season as it gives specific times during Quarters, excellent for totals betting.
Soccer/Tennis-
www.livescore.com (This is the best i found in terms of compatibility to a mobile phone.
NFL-
www.nfl.com (Also very good, similar to NBA setout)
NHL- People who like ice hockey probably cant work a mobile phone anyway.