It's proven useful in a couple of places, and it's pretty small and self-documenting. I had written this mainly to look at my VS settings file in a nicer way since it saves with a minimum of whitespace.
private static string ToPrettyXml(string xml)
XmlDocument doc = new XmlDocument();
using (StringWriter sw = new StringWriter())
using (XmlTextWriter xmlWriter = new XmlTextWriter(sw))
xmlWriter.Formatting = Formatting.Indented;