Nanoweights: 25g
Fleaweights: 75g
Antweights: 150g
Beetleweights: 1.5kg
Featherweights: 13.6kg (30lbs)
Heavyweights: 100/110kg

I actually use arduinos in some of my bots but the truth is that they aren't really needed in most bots. I use arduinos to enforce custom control and limit switches on axes but most other bots I run don't need them.