Eric Lippert is a prolific writer and is amazing at explaining anything related to computer programming. His blog is a MUST read for every .NET developer: http://blogs.msdn.com/b/ericlippert/

I also follow Eric's activity on SO here:

http://blogs.msdn.com/b/ericlippert/*

edit: also thanks for making me spend probably next several hours reading through all that stuff :)

edit2: oooh this one is good as well http://stackoverflow.com/questions/3110154/why-is-the-explic...

edit3: Not from Eric but check out this C# code:

    sbyte[] foo = new sbyte[] { -1 };
    var x = foo as byte[];    // doesn't compile
    object bar = foo;
    var f = bar as byte[];    // succeeds
    var g = f[0];             // g = 255