Someone will do better than I, but off the top of my head...
1. A woman's hair is her glory and serves as her covering.
2. A woman should wear a physical covering while praying or prophesying in corporate worship.
3. A woman should wear a physical covering while in corporate worship. Some extend this to all teaching, prayer meetings, etc.
4. A woman should wear a physical covering at all times because we are to cover when we pray, and we are to pray without ceasing.
5. That was then, this is now; a cultural mandate for that time period only.
I'm sure I've left out a view, though.
Hope that helps. (I am in the third camp, btw.)