Looking at the DateTimeFormatInfo documentation, it appears that all the standard formats have colons in them, which makes passing them on a url unpleasant/impossible.
I'll put everything together into one answer:
You could do something like this:
string urlSafeDateString = HttpServerUtility.UrlTokenEncode(date.ToUniversalTime().ToString(System.Globalization.CultureInfo.InvariantCulture).ToCharArray());
DateTime date = DateTime.Parse(new string(HttpServerUtility.UrlTokenDecode(urlSafeDateString)), System.Globalization.CultureInfo.InvariantCulture).ToLocalTime();
Or you could do something like this:
string urlSafeDateString = date.ToUniversalTime().ToString("yyyyMMddTHHmmss", System.Globalization.CultureInfo.InvariantCulture);
DateTime date = DateTime.ParseExact(urlSafeDateString, "yyyyMMddTHHmmss", System.Globalization.CultureInfo.InvariantCulture).ToLocalTime();