Working on the F1 contest and one of the things I found tricky was getting the Normal direction right. Finally got them fixed, but then it hit me today, because I had revisit the topic, a nice easy solution to tell what is pointed which way...

CHANGE THE COLOURS! Normals pointing inside could be dark blue, pointing outside could be that nice turquise it is now.

I had to group them eventually by making inside & outside pointing normals different materials, then I could select by materials, but a select by Innies or Outies would be nice too

(I DO hope this isn't already done, or I'll be real embarrassed. I couldn't find anything about it though!)

I have two methods

one: textured mode after entering and exiting face mode: press [F] twice
faces will be visible (white likely, if you like how they are in shaded control+z mode press the make vertex colors button in the edit buttons after exiting face mode) from one side.

two
unpress the double sided (top right) button with your object selected in the edit buttons. The faces when viewed in solid mode [z] will be black if you are looking at their back side.

you know about the draw normals button in the edit buttons too right?