gel electrophoresis - Alternatives to ethidium bromide for staining small nucleic acids?

While ethidium bromide works well for staining larger single-stranded RNA or double-stranded DNA molecules, it doesn't stain smaller nucleic acids very well. I observed that at around 20 bases and below single-stranded nucleic acids are difficult to see with EtBr-staining unless the nucleic acids are highly concentrated.

What are good alternatives for observing small nucleic acids in polyacrylamide gels? The main consideration would be ease-of-use, and it should be possible without any unusual equipment.