I take my DSLR bare on Splash Mountain - it's a D7k series so it's weather sealed, as are my lenses, and even with it getting pretty wet there's no issues. Only Kali is an issue for a fully weather sealed camera.
For lower end bodies without weather sealing or only partial weather sealing, like a Canon Rebel, Nikon D3k/D5k or Dxx body and/or without a weather sealed lens (most recent Nikkors, can't speak to the Canons), a LowePro AW case is your best friend (they kind of are anyway, they're very good products).
I also use a BlackRapid strap with BRAD so it can stay attached to me no matter what when they're not in the case.