[clayne]

That thing is good for (as the name suggests) dropping exposed film into (though too small, i find).
But impossible to use to carry unexposed film in - you can't get at it.

Lowe make (made?) small bags called (if i remember correctly) 'film organisers'. They are quite good, hold a quite nice amount of film. I carry my film in these thingies, clipped to my LowePro equipment bags.
But they don't really provide a quick way to pick a film of one type when loaded with different types. They come with one divider, and i found that even with only two types of film you will have to be careful not to grab the wrong type.

Yeah I was looking for that kind of bag but couldn't find it. Either way if one just grabs a few rolls out of the bag they'll be statistically likely to have grabbed a roll of the type they wanted. Same bag issue everyone else has when they can't 100% see the film that's in it.

Edit: one of the Lowepro lens cases would probably work just fine.