This is probably a bit obvious, but a claminping set would be number 1 on my list. If you're going to hold lots of odd shaped objects maybe a couple. And packers to support things, I use a couple of pairs of cheap 1-2-3 blocks which have been handy for supporting jobs. And, if you haven't already got one, a good quality DTI for clocking jobs up and locating from datum holes -and a suitable adaptor for holding it in the machine. I don't have one but I particularly like the double-elbow ones that slacken off and lock all the joints with one screw, very easy to use.
Regards
Kevin