With the 1.6.x updates, a "feature" was added which made fences burn. Now, I understand that making a wooden fence burn adds realism, but this was a bit upsetting to some people as their creations involving fences and lava were destroyed. This is what I am suggesting: Notch should create different types of fences. There should be stone fences which are not burned, and steel fences which do not burn and protect from creeper explosions. I feel that this would allow for users to re-create their demolished creations. I believe that there is in fact a mod for this but i feel that it should be added into vanilla. Feel free to post your opinion.
One of these http://ekoti.files.wordpress.com/2011/05/heathers-at-small-stone-wall.jpg
As for an iron fence I think those would be lovely...