I've done this passively but now I might amp it up since I checked my adsense account today. $27.00 and I posted my site once 4 days ago. Get a couple gmail account, post in the major cities on CL, get traffic and clicks. Make a website that is mainly adsense. Buy a domain that will forward to your adsense website. Market domain (with an ad on Craiglist) people will type in your domain, get forwarded to your adsense website... browse around and most of the time click the links. Try to do it 3 times a week and watch your adsense account build up... maybe $200-$300 a month or more depending on the category you go for. You can also have live links on CL but they will burn out so make sure you don't use your adsense website as a live link. CL will eventually block and Google will catch on (referrer) and nix your account.