Fixies are dangerous but some common sense can go a long way.
But REALLY not for the street. Single speed freewheel is the way to go. You can also get a freewheel with two different sized cogs and a small chain tensioning device. Makes it easy to move between cogs. For up hill etc..
My biggest fear is getting something caught between the chain and front cog whilst riding... If its a toe
Crushed and twisted mess. Trouser pants... Torn and oil stained.