OK...
Your very first effort, "Large Alex", is our T-shirt design. Any questions? :)
I actually like the text overlapping the doggie in that one, though I'm not sure it would work for the smaller versions. Also, I like Alex being bigger than the text, I wonder what it would look like if you maintained a bit of that flavor in the smaller versions?
As far as the button goes, I wouldn't mind a slightly more rectangular version. That would let you put a slightly bigger Alex to the left, and "powered by Open ACS" in the same vertical arrangement you've showed to the right.
OK, now you get to tell me how to hack Tcl for a week :)
Seriously, these are just ideas spawned by your efforts. They're all very good.