How many of these can be made with the X-Carve?
Not many if any — unless one uses a flip or other specialty jig — a 3-axis CNC is quite constrained in what it can cut, and where it will leave rounded edges.
Knapp joints were one of the first designed to be cut w/ a router: http://www.shapeoko.com/wiki/index.php/Fabrication_Techniques_%26_Hardware#Knapp_Joints — see the following section for a link to a CC-licensed discussion of joints suited for cutting w/ a CNC.
I am pretty sure this one can be made without even needing to do a two sided carve.
I think most of the others are possible if you do 2 sided carves. Way to much trouble to be a practical method of joinery, but still an interesting way to make a join without glue.
That one depends upon squared off edges to hold — it’d only work properly if one did a post-processing cut w/ a file or float or chisel or saw — if you modified it you could instead use a rounded floating tenon/key but that would create some fragile end grain.
But, will grant that it would have been more accurate to say one, perhaps two.
I like these techniques.