DateTime.ParseExact(...)

Another gem in .NET 2.0. Parsing a string to get a datetime used to be pretty complex. But now with the DateTime.ParseExact(...) method you can specify the exact format of your string.

string s = "20071231T214559";
DateTime d = DateTime.ParseExact( s, "yyyyMMddTHHmmss", null );
this.textBox2.Text = d.ToString();  // this will print: 31-12-2007 21:45:59

Steve Tibbet has a post describing all the options for specifying the format.