I'd suggest standard resistor values in decades: 1 ohm, 2.2 ohms, 3.3 ohms, 4.7 ohms, 5.6 ohms, 6.8 ohms, 8.2 ohms. Then multiply by 10: 10 ohms, 22 ohms, 33 ohms, etc. Keep going until you reach 1 megaohm.
Even if you don't have the exact resistor you want you can probably cook it up by placing two resistors in series or parallel.
You could just buy the motherlode as a single item (if you have the $$$):http://search.digikey.com/us/en/products/Q17361/RSQ200-ND/51507
But you could probably get a subset of that yourself for cheaper
The Rugged Motor Driver
: two H-bridges, more power than an L298, fully protected