JT:
Feh, a 9-ball rack is actually good for somethin'?
I use a standard triangle rack (a good one, in my case, a Delta-13), but I point it 90-degrees clockwise (or 90-degrees counter-clockwise, depending on which way you prefer the apex of the rack pointing). In other words, position the rack such that the apex of the rack is pointing to just under the second diamond (just under the footstring). Then, rack the balls inside of it in the usual 7-ball "flower" pattern with the 1-ball on the footspot, scrunching the flower sideways into the apex of the rack. (E.g. if the rack is turned 90-degrees clockwise with the apex of the rack pointing to the racker's righthand-side rail, using the left hand to push the flower to the right into the apex of the triangle.) It takes a quick getting used to, since you're applying sideways pressure to tighten the rack, instead of applying forward pressure towards the headball. But it works, and works well. A Delta-13 gives a very tight 7-ball rack in this manner. No need to add an extra ball, then have to take that extra ball away after you remove the rack.
I wish CueTable offered a triangle rack as one of the objects that can be placed on the CueTable surface, but unfortunately, as far as I can tell, it doesn't. (Otherwise, I would've included a CueTable diagram of what I'm talking about.)
Hope this makes sense,
-Sean