I echo the sentiments here re. post-dinner nibbles. Something we've found helpful is to declare the kitchen closed after dinner - it's just a psychological thing (although come and declare it on here if it helps!); and for a physical "symbol" of kitchen-closedness, as Hairspray says a peppermint tea or coffee can be really helpful. I quite often have a rooibos with a squeeze of vanilla soya milk: a tiny bit sweet but hardly any calories. Alternatively those good old Options Hot Chocolates are miraculous if they placate the sweet craving for you.
Ultimately though, it's just about retraining your body and (more importantly) brain, so in spite of all these little hacks, the real challenge is, as Kiki says, to just not give in to it. You'll be surprised how quickly your brain stops clamouring for dessert once you stop giving in to it. I used to drink wine with my dinner almost every night and found it really hard to stop - pouring a nice cold glass just meant "OK, day over, evening begun" and it was so hard to kick, but now I don't, just simply don't drink Mon-Thurs, and so it just doesn't occur to me any more.
The master of this is TVHubbyClaire though, he has the sweetest tooth on the board so I'm sure he'll come along to offer sympathy and advice soon!