Thanks, IJ. Using 6 servos here. I can either hard code it (trial & error) or use an IR remote or keyboard as a teach pendant and use record & playback modes. Lots more impressive stuff to come. Built the arm for a PICAXE feature in upcoming ROBOT magazine, May June issue, due out in March. Part one of my series is on newsstands now, a basic intro to PICAXE.
BTW, the miniature 5/8" wooden alphabet blocks I used are quite handy here and in other projects, robotic or otherwise. They are available at a discount (for $3) if you mention ROBOT magazine when you order at http://www.helpinghahns2.com/product_p/abcblocks-small.htm One set is 15 two-sided blocks. You need 2 sets for one full alphabet.
Rock solid repeatability so far, no recalibration needed. But servos are mechanical and certainly have limits. The more you use them, the internal pots and gears will wear out. These Hot Wheels weigh ~35 grams, on the heavy side for an arm this small. So here I'm operating them at a small radius, which keeps the servo loads low. Lifting heavy things at the outer edge of the operating range would dramatically increase the servo loads and cause more wear. I'm not in any hurry to damage the arm, it was built for accuracy, not payload.