Most of the common types have a “TryParse” method available.  Here’s a method you can use to dynamically call the corresponding TryParse method for a specific Type:

public static T ConvertValue<T>(string stringValue)
{
    if (typeof(T) == typeof(string))
        return (T)Convert.ChangeType(stringValue, typeof(T));

    var type = typeof(T);

    bool nullableType = type.IsGenericType 
        && type.GetGenericTypeDefinition().Equals(typeof(Nullable<>));

    if (nullableType)
    {
        if (stringValue == null)
            return default(T);

        type = new NullableConverter(type).UnderlyingType;
    }

    Type[] argTypes = { typeof(string), type.MakeByRefType() };

    var tryParse = type.GetMethod("TryParse", argTypes);

    if (tryParse == null)
    {
        string exceptionMessage = string.Format("A method named 'TryParse' does not exist for the '{0}' Type.", type.FullName);
        throw new InvalidOperationException(exceptionMessage);
    }

    object[] args = { stringValue, null };

    bool successfulParse = (bool)tryParse.Invoke(null, args);

    if (!successfulParse)
        throw new InvalidCastException();

    return (T)args[1];
}

I’m currently using this in a code generation scenario where I have a string value and “T” is known at generation time.  Enjoy.