You can be a chocolate snob like me and still not rely on child slaves to get the stuff to your table. Many of the fair-trade, organic chocolate bars have failed miserably to impress me, but just as many have knocked my socks off with how good they are. Here are my recommendations:
For cooking cakes etc: Green & Blacks or GEPA dark chocolates, Plamil for cases where you want a dairy-free milk or white chocolate. Green and Blacks also makes kick-ass coco powder.
For super decadent stuff (truffles, hot chocolate): Valhrona, either tempered or not, depending on the application.
For straight up eating (decadent): Coppeneur, Charlemagne, Coco of Bruntsfield, Luento Santoro
For straight up eating (fun): Dagoba (if you can get it fresh-ish... I don't know why, but I've had extremely bad luck with getting stale/bloom-ish chocolate from this company, yet their lavender chocolate is so good, I still buy it.)
Generally, stuff marked organic (or fair trade) is slave free, as is single-origin chocolate that is not from the Cote d'Ivoire. Please do your sleuthwork if you are unsure of the origins of your chocolate. Here is a link to a list of some slave-free chocolates. If you're too lazy to do your own research, please please please stick to the brands that others have taken the time to research for you.