I wonder if there is something like a standalone Version of Visual Studios \"Immediate Window\"? Sometimes I just want to test some simple stuff, like \"DateTime.Parse(\"bla
Linqpad - I use it like this all the time. http://www.linqpad.net/
Don't be misled by the name - that just describes the original motivation for it, not its functionality.
Just recently he released a version with proper statement completion - that's a chargeable add-on (the core tool is free), but a minute amount of money and well worth it, I think.