Everyone loves extension methods!

Useful C# Extension Methods

public static bool IsNumeric(this string s)
{
    double d = 0.0;
    return (double.TryParse(s, out d));
}

public static int? ToIntegerNullable(this string s)
{
    int i = 0;
    if (int.TryParse(s, out i))
        return i;
    else
        return null;
}
public static int ToInteger(this string s)
{
    int i = 0;
    if (int.TryParse(s, out i))
        return i;
    else
        return 0;
}
public static double ToDouble(this string s)
{
    double d = 0;
    if (double.TryParse(s, out d))
        return d;
    else
        return 0;
}
public static decimal ToDecimal(this string s)
{
    decimal d = 0.0m;
    if (decimal.TryParse(s, out d))
        return d;
    else
        return 0.0m;
}
public static string ToFormattedDateTime(this string s)
{
    DateTime dt;
    if (!DateTime.TryParse(s, out dt))
        return "";
    else
        return dt.ToString("dd MMM yyyy");
}

public static UserDetail GetUserDetails(this MembershipUser user)
{
    Model.Entities _db = new Model.Entities();
    return _db.UserDetails.Where(ud => ud.Email == user.UserName).First();
}

public static List<string> AppendPleaseSelect(this List<string> list)
{
    list.Insert(0, "Please Select..");
    return list;
}