Any ideas on what activities to do on weekends with my 6 yr. old?

Are there any kids in your neighborhood for him to play with? That would give you a break. You could introduce him to educational video games, get him board games, take him to the library (sometimes they have free weekend events), color with your son (or have your hubby do it), find out if there are any free events (outdoor is the best) going on in your town and take your son to tire him out a bit and keep him occupied. Call in reinforcements - grandpartns, cousins, aunts or uncles - to take them to events on the weekends or to babysit so you and your hubby can get a night out. To help you - nap while your hubby is playing with him.