Late to the party here. I lost about 35 pounds last fall, gained 15 or so of them back over the holidays and the first half of this year, and am back on the wagon as of this week.
My secret weapon is WWCalc, an unofficial Weight Watchers application for the Palm. I am a big-time stathead, so I dig a system that breaks stuff out into points (calories and fat = bad, fiber = good, exercise = bonus points) and helps me keep a handle on portion control.
I hear Jough on his comment earlier on figuring out the calories in some recipes being a pain in the ass, but I do it. recipecal.com is a good site for getting nutritional information on particular ingredients. Sometimes I'll figure out the calories, fat and fiber in an entire dish, then break it down by portion size. You quickly learn what is and is not your friend, and adjust your cooking accordingly--cutting back on the oil and butter, f'rinstance. Carbs are OK in moderation, which can of course be difficult.
Word up on wombat's farmer's market suggestion. A good idea is to buy crazy-ass vegetables that you aren't familiar with, and then you have to track down recipes and figure out if you like them. I freakin' love bok choy as a result of being in a CSA a few years back.