Money.cs

/// <summary>
/// Represents a monetary amount for a given currency. 
/// Allows easy representation and conversion of monetary values.
/// </summary>
public class Money
{
    /// <summary>
    /// Amount of money
    /// </summary>
    public readonly decimal Amount;
        
    /// <summary>
    /// Currency of money
    /// </summary>
    public readonly string CurrencyCode;
        
    /// <summary>
    /// Creates a representation of the designated
    /// amount, using the current culture as currency.
    /// </summary>
    /// <param name="amount">Amount of money to represent</param>
    public Money(decimal amount)
        : this(amount, CultureInfo.CurrentCulture.Name)
    { }

    /// <summary>
    /// Creates a representation of the designated
    /// amount for the provided currency.
    /// </summary>
    /// <param name="amount">Amount of money to represent</param>
    /// <param name="currencyCode">Currency to represet money as</param>
    public Money(decimal amount, string currencyCode)
    {
        Amount = amount;
        CurrencyCode = currencyCode;
    }

    /// <summary>
    /// Converts money from one currency to another. Keep in mind
    /// this doesn't do an exchange rate, it simply converts the 
    /// representation to a different currency.
    /// </summary>
    /// <param name="currencyCode">Currency to represent new money as</param>
    public Money Convert(string currencyCode)
    {
        return new Money(Amount, currencyCode);
    }

    /// <summary>
    /// Formats money using the appropriate culture
    /// </summary>
    public override string ToString()
    {
        return Amount.ToString("C", CultureInfo.CreateSpecificCulture(CurrencyCode));
    }
}

could improve via Equals, GetHashCode, and static operator overloads