Colin Eberhardt has posted a neat multi-purpose value converter that tries various conventional conversion methods to convert from one type to another. This overcomes a frustrating limitation in WPF/Silverlight data binding where the XAML parser is seemingly more intelligent at converting literal values to target types than values sourced from binding expressions.
Unfortunately, the TypeConverter usage will not work in Silverlight but perhaps using the XamlReader technique there’s something that could be done?
Also, a couple of the readers in the comments had a great suggestion to derive the converter from MarkupExtension to simplify the XAML. I think I’m going to have to go back and do that with all of my converters now.