public class ForeignKeyConverter : IValueConverter
{
    public object Convert(Object value, Type targeType, object parameter, CultureInfo culture)
    {
        DataRelation relation = parameter as DataRelation;
        if (relation == null)
            return value;

        var nameQuery =
            from rows in relation.ParentTable.AsEnumerable()
            where rows.Field<int>(relation.ParentColumns[0].ColumnName) == (int)value
            select rows.Field<string>("name");
            
        return nameQuery.FirstOrDefault().ToString();
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return null;
    }
}