I would add a nice set of electrolytic capacitors, some LEDs, a few larger inductors for switchmode regulators and a few smaller for signal filtering (like uC ADC filtering), large quantity (because they're dirt cheap) rectifying and signal diodes, perfboards of different size, different guage wire, bipolar transistors (large quantity of both small, 100 mA NPN and PNP), some power MOSFETs, a few Schottky diodes, opamps of all kinds and devices per package, 555 timers, MC34063.
I think this covers most of the basic parts I needed for just playing around. I also love building circuits with 7400 and 4000 series of chips, they have a little of magic in them and I collect all the different chips I can find.