Want an advanced degree in diaper rash management? This excellent article from Pediatric Nursing takes you deep into the world of diaper pastes, for when Desitin just isn't cutting it anymore:
Me, I'm a big fan of the descriptively named Boudreaux's Butt Paste for your basic diaper rashes and irritations. It works well, smells good, and, well, it's called Boudreaux's Butt Paste.
Another good option is Triple Paste. I use this on raw diaper rashes that need a really tenacious barrier paste.