Generate a "slug" for a URL from a string

slug.cs

public static string ToSlug(this string message)
{
    // replace space with -
    message = Regex.Replace(message, @"[\s/\\\.,+|_]+", "-");

    // normalize the message
    message = message.Normalize(NormalizationForm.FormD);

    // do simple DK char replace
    message = message.Replace("ø", "oe").Replace("Ø", "Oe").Replace("æ", "ae").Replace("Æ", "Ae").Replace("å", "aa").Replace("Å", "Aa");

    var result = new StringBuilder();
    for (int i = 0; i < message.Length; i++)
    {
        UnicodeCategory uc = CharUnicodeInfo.GetUnicodeCategory(message[i]);
        if (uc != UnicodeCategory.NonSpacingMark)
        {
            result.Append(message[i]);
        }
    }

    return Regex.Replace(result.ToString().Normalize(NormalizationForm.FormC), @"[^a-zA-Z0-9\-]", "").ToLower();
}