Single Stranded DNA Specific Stain

[billing at vetsci.microvet.arizona.edu]

Is anyone aware of a stain that is specific for single stranded DNA?  I 
seem to recall something about acridine orange, but the ol' brain cells 
can't be certain.

I am trying to find an easy method to detect single stranded 
plasmid intermediates on agarose gels?  If not specific stains, any 
other ideas?

TIA

Steve