Wanted: Your tips on Rio de Janeiro

Hi – I’m down to Rio de Janeiro next week on business.  Pretty busy schedule, but I’m hoping to squeeze in as much interesting stuff as possible.  Any advice on:

– Things to do?  i.e. advice on things that must be seen/heard/felt/eaten?
– Security?  (especially beyond common sense tips for any big city)
– Other general dos and don’ts?

Thanks for your help!