When you say "jigs" - most people think of either material tied jigs and/or plastics on a lead jighead. You've already found that by simply putting a minnow on an "undressed" jighead works as well.
I'm going to step out on a limp and say that - on average - most crappie fishermen throwing jigs are using 1/32oz. and 1/16oz. I've read of guys using up to 1/8oz. and down to 1/80 oz., but I believe these sizes tend to be on the outer edges of teh weight scale for crappie. There will always be exceptions.
Color choices are very broad as well. If you look through some of the past threads, you will see chartreuse comes up pretty often - that seems to be a pretty safe bet. Here again, everyone has their favorites - their confidence color(s) if you will.
White, yellow, black, red, chart., and orange are all good starting points (or any combination of these colors).
Zigs Jigs - bet you didn't see that comin' did ya? :DIf you had $30-$40 (do I need more?) to spend on jigs for the year, what would you get?